Sometimes your MySQL queries or tables may stop working. If you get an error which says, "so-and-so is marked as crashed and needs to be repaired," then you can easily fix this in cPanel.
Even if you are getting a different kind of error like "supplied argument is not a valid" or "table attribute does not exist", then you can use this test to try and fix the problem.
Step 1 - Log into cPanel (click here for a guide)
Step 2 - Find and click on MySQL Databases icon
Step 3 - (1) Select the Database you would like to repair, then (2) click Repair Database
Once the repair is complete you will get this screen: