You can backup your account files and you should do that at least once after you created the account. This ensures that you still have your private key to access your account if anything goes wrong.
Simply use the backup functionality. Backup files are stored under /backups and you can and should manually backup them also from time to time. This is considered the most comfortable method. If required you can restore the backup via the GUI. Later you sync again with friends and everything is fine.
When you create your account your private key file is also exported to control/keys/ directory. Better backup it, too. The name of your key is your address.
In the control/keys-folder you can find all the private keys of the accounts you have created on this machine. If control/keys-folder is a shared network resource then of course it contains all the keys of the clients that have access to this shared network resource.
And of course, do not forget TSA query and response of your account:
/proofs/YourAddress/freetsa.tsq
/proofs/YourAddress/freetsa.tsr
If for whatever reason all you have is these four files you still will be able to restore your account. But it will be more work to restore it as only placing these files back into the related folders is not enough. E.g. the private keys then have to be manually imported to the keyring.