Guides
Read the error before you pay for anything
Most Access failure messages describe a check that failed. The damage itself is often somewhere else. These guides go through the checks in the order worth running, including the cases where the file is fine and the answer is a Windows setting.
Before the reading
If you only want to know whether your file is readable
The check runs in your browser and reports per table what the database claims, what was read back, and what could not be parsed, before any payment. It is the fastest way to find out which of the guides applies to you.