ULX groups are stored in gmod\data\ulib\groups.txt, users for groups are stored in gmod\data\ulib\users.txt
Utime data is stored in gmod\sv.db (the root gmod server folder)
If by 'ranks' you mean admin "groups", they have nothing to do with the same file area.
If by 'ranks' you mean something actually called 'ranks' in a gamemode, then it's possible whatever stores ranks are also in sv.db
No matter, it sounds as though your sv.db has been erased/modified/or corrupted.
If you do not have a recent backup of your gmod\sv.db file from recently, your UTime data is gone.