Whatever "messed up" means...
Depending on OS.
1) If you did rebuild (to add packages), then there is
- On Windows) a lazarus.old.exe in the install dir. (back it up now, or next time it may be bad too)
- On Linux) start lazarus as "lazarus" and not "startlazarus"
2) Config
- Win) C:\Users\USERNAME\AppData\Local\lazarus
- Linux) ~/.lazarus
Backup, then remove individual XML files, until you found the guilty one