how can I repair .accdb file corruption

Here are some best fixes to resolve this damaged issue.  You can apply any of the following.

SOLUTION 1: Create New Macros Or Module

If you suspect that the damage is in your macro or module; you could make a new macro or module and then copy the undamaged contents of the original macros or module into it.

SOLUTION 2: Non-ASCII Characters Removal

Sometime the reason of the damage is also the non-ASCII characters that are creeping into the module. So try to save the file as the text file and remove all the illegal entries, if it contains. Save the file and reload it.

SOLUTION 3: Access Repair Software

If in case the above solution fails then you need to reach out to Stellar Repair for Access for advanced troubleshooting and solutions of MS Access Database issue. There are various advantages of using this tool such as it repair corrupted/damaged .accdb and .mdb files, restore each and every data and such as reports, tables, queries, macros,modules, forms, etc.