Well. First step: get v2.5.0.1 (can be found on the debug builds page here:
Shareaza - Debug Builds). Use a 32 bit build (if you're working on a 32 bit OS, which should be the case). If you whish to report other bugs, use the debug build, else, use the release build (which uses a bit less CPU).
Is the transfers window still empty after the install?
How many transfers did you loose?
if you didn't loose hundreds of downloads, I'll describe you an easy way to get them back with some work:
1. create a magnet link for some random file out of your library.
2. Move your incompletes to a different folder
3. For each incomplete (except for the torrents, which will be lost unfortunately), use your magnet delete everything out of your created magnet link (1.) except for the type of hash included in the filename. Now replace the hash of your magnet link with the hash included in the filename.
4. enter the newly created link into Shareazas search window input area and hit enter (followed by "download")
5. Now use the "merge with local file and verify" feature for the file you've just added and choose the matching partial file.
6. repeat this for all .incomplete files.
PS.: Merging might not work before the download has fond some sources, so just add all files to your download list using the described procedure and merge after all your downloads have been merged again.