I think the first thing to note is that an SDLTM is quite robust.  However, there are things you can do that might be the cause of your TM getting corrupted.  For example:

• sharing your SDLTM file-based TM on a network drive, dropbox, onedrive etc. with others without taking sensible precautions to avoid all users writing to the same file
• working on something like OneDrive where your SDLTM is being updated as you translate and at the same time is being backed up with every transaction.  If the network connection isn't fast enough you can cause corruption by writing to the TM before it completed it's previous back up.  The larger the TM becomes the more susceptible it is to this problem.

If it does become corrupted then TM Repair can often repair it.  But not always.  If the TM is too badly corrupted it may not be possible to recover it at all.  I have had limited success using a tool called SysinfoTools SQLite Database Recovery:

But it wasn't always straightforward, but with a combination of this tool, an export to a text file, then some regex cleanup, and I have been able to recover large text only translation units which is better than nothing.

So the other important message to take from this is backup, backup, backup!  I'd recommend running a backup when Studio is closed and not in real-time as you use it, maybe at the end of each day as you see fit.  I'd also recommend you export to TMX as well from time to time.  Since a TMX is a flat text file it's much easier to recover data from it and make it available in a variety of tools.