These instructions are the same whether you're trying to seed your own torrent and you find you've checked in as a leecher at 0%, or whether you're returning to someone else's torrent where you previously completed the download and find you're entering it as a leecher at 0%. For the 99% problem that makes a difference, but for the 0% problem it doesn't matter.
The 0% problem comes when your client looked in the wrong place for your source files. Either you've set it always to use a default download directory, and it looked under there instead of asking you where your source files are; or when it asked you which directory to use, you gave it the wrong answer.
But either way, it didn't see your source files, so it assumed that you didn't have any, and that you were joining the torrent as a brand new leecher in order to download a copy.
Then it confused the issue by creating a subdirectory with the right name and a bunch of files inside it with all the right names. But they're just placeholders, either empty or filled with garbage bytes, waiting to receive what your client thinks it's going to download. If you just look at the subdirectory name and the filenames, everything looks right, but those are not your real source files; the real source files are somewhere else on your hard drive.
You have to tell your client not to use a default download directory and not to use fast resumption (for example, in BitTornado from version T-0.3.0 on, you click Prefs, set "ask where to save" to ALWAYS, and click Save to record the new preferences; in the official client from version 3.4.2 onward, you click View, then Settings, and then for "ask where to save each download" you pick ALWAYS). Then disconnect from the swarm and then go in again. When you get your client to ask you which directory to use, lead it to the right one, and don't be fooled by the directory full of dummy files that got created on your first try.
CAUTION: most clients require you to pick the directory that contains the top directory of the torrent; see Archive.org's copy of Brian's BitTorrent FAQ and Guide for details about that.
When you find the right place, your client will analyze the files to compare them to the hashes in the .torrent file and see how much of the torrent you have; since you're the initial seeder, that should be 100%. Then it will check you back into the swarm as a seed if everything has gone well. (If it finds some of the content but less than 100%, you have another problem. We can talk about that if happens.)
If your client doesn't analyze your existing files but jumps back in as a leecher again, it's still looking in the wrong directory.
Some clients support other ways around it: for example, Azureus 18.104.22.168 and earlier had an "open .torrent for seeding" function that made sure that it found the source files *and* that they matched the hashes fully before it would check into the swarm at all. (The "open for seeding" selections in newer versions of Azureus, in µTorrent 1.5, and in BitComet are not the same, and in fact are harmful.) ABC, µTorrent, and versions of the official client from 4.0.1 onward have a "change directory" or "change location" feature: you stop the torrent job in the client, tell it to use a different local directory. So try again, and make sure you have your client looking in the right place for your files.
In µTorrent for Windows, for instance:
- Highlight the torrent's line in µTorrent's upper pane. We'll call that line the torrent's "job".
- Click the STOP button.
- Right-click the torrent's job, choose "Advanced / Set Download Location".
- Choose the folder containing the relevant files (if you use µTorrent 3.0 or later despite their not being among our recommended clients, choose the parent of the folder that contains the relevant files) and click "OK".
- Right-click the torrent's job again and select "Force Recheck".
- Click the START button.
Or in Transmission,
- Ctrl-click on your torrent file in Transmission
- Choose "Remove from list"
- Then File>Open Torrent File
- Go and find the torrent file you downloaded from DIME
- Choose "Open"
- Click "Change" and in Finder, select the folder one stage above the folder that contains the files. For example, don't choose the download folder name, choose the folder above that.
- Click "Select"
- Click "Verify Local Data" and confirm that each file reaches 100%
- Then click "Add"
SPECIAL NOTE to users of version 4.0.0 of the official client: that release had a bug that prevented directing it to the proper folder and caused a 0% problem. Upgrade to a later release (up through 4.20.9, or 6.0.0 or later, but not any version of Mainline from 4.22.0 through 5.0.9) or change clients.
SPECIAL NOTE to users of BitTornado: see BitTornado Quirk for another way you can run into a 0% problem with BitTornado, even when you know you're selecting the right directory.
SPECIAL NOTE to users of Azureus or Vuze: once Vuze/Azureus has looked at the wrong directory, it can be difficult to persuade it to look anywhere else, but it is possible and many users have done it. If you have a 0% problem with Vuze or Azureus, you may find it easier to seed the torrent with another client on DIME's recommended client list. Do not post another torrent of the material; use another client to seed the torrent that you've already posted. You do not have to uninstall Azureus or Vuze and you can go right back to it for the next torrent you enter.