Could be a bad install or a corrupt save file, it's hard to tell without an error message. Luckily we have solutions for both.
First off, run your patcher.exe in your Pokemon Uranium folder to ensure that you're running the most recent version of the game and see if that fixes your issue.
Secondly, assuming it's your save, head into C:\Users\<Username>\Saved Games\Pokemon Uranium\Backups and retrieve your backup save. Make a copy of your current save to keep it from being overwritten and then place your backup save in your Saves folder.
If that doesn't work, download and re-install Pokemon Uranium using the download link we keep on our
Official reddit page then run the game patcher one more time.
If none of these work, send me any error message you receive and I'll forward it to the rest of the dev team.
Backup your saves, don't lose progress!
C:\users\<Username>\Saved Games\Pokemon_Uranium
Save Backups:
C:\users\<Username>\Saved Games\Pokemon_Uranium\Backups
OID: 000003 OT: Cody