If you have a backup of your 4images database, great. My advice is to do a clean install as if you were installing 4images for the first time. Create the same admin id and password that you used before.
Upload your database backup to 4images/data/database. Then from the admin control panel, use the "Backup Database" to restore your backup.
If you've already tried these steps, then I really don't know what the problem could be. Do you have any more info on this?