If your issue isn't listed here, or the troubleshooting steps aren't working for you, feel free to ask in our communities:
Common troubleshooting steps
Things to try in case of trouble
Solving recording problems
When your recording doesn't seem to work as it should.
Recovering corrupted projects
Project doesn't open anymore? It likely can be recovered
Error codes
Causes and potential solutions to various error codes
Solving other problems
Various other solutions to various other problems.
Missing features
If you upgraded from an earlier version and miss a feature, here's where it went.
Resetting Audacity