A screen shot of what actually fails would help determine your problem. It’s not clear what version of AxCrypt you’re running now, nor what preceeded the current problem.
Two situations are common:
1) You’ve downgraded to version 1, and you can’t open some files because they were upgraded to version 2 automatically when you did use version 2.
2) You upgraded, set a password, opened some old files which were upgraded and re-encrypted with the version 2 sign in password. Then you came back, realized you’d forgotten the sign in password and issued a password *reset* for the account. Now you have some files which are encrypted with the forgotten password.