Assuming you were on 5.5.1 before upgrading, you need to do 2 things:
- Revert the database by restoring it from the backup you made before upgrading.
- Edit the last line of config/site.php to point to 5.5.1 (or delete if it was originally a 5.5.1 fresh install)

The same strategy can take you further back, but becomes more hazardous the further back you go.

Take database and file backups before attempting this. That way, at least you can always get back to the current state of your site.

Thank you, but where do i find the file to edit? Sorry but i am not very adept at this.

Don

Look in the directory
root/config/site.php

If the site is online, you will need ftp or ssl to get to this.

Ok, i guess i am an idiot, have no idea where to find these folders.....lol. Thanks for the help.

can i find these folders someplace from the Dashboard?

These are folders in the web host's file system, not in concrete5's file manager. You should have access to them through the login facilities you web hosting company gives you.