I lost my character in Terraria, how can I get it back?

Solution 1:

It sounds like your savegame is corrupt. The only solution to that, is to restore a previous savegame. You'll lose some progress, but it's still better than to lose everything.

If you're playing on Windows and have enabled OneDrive's Folder Backup feature before your savegame got corrupted, you can easily restore a previous version of your savegame. Each version should have a timestamp to help you identify a version that is uncorrupted. You can find your savegame in:
OneDrive\Documents\My Games\Terraria

If you don't use OneDrive (you're not on Windows or don't want to use OneDrive), you'll need to restore your savegame from a backup instead. Obviously, this is only possible if you have made at least one backup before your savegame got corrupted.

If you don't have a backup, then I strongly recommend you consider making one to avoid a situation like this in the future. Both Windows and macOS can make hourly automatic backups. Windows 10 has File History, while macOS has Time Machine.