The most important disks, on the UNIX, and Window systems are backed up on a regular basis with incremental backups each work day and full backups every week or so. So, if you loose a file it should be possible to recover the version that existed on the previous work day. However, as the backup systems fill up old backups will be removed, so if you don't realise you have lost a file for several weeks, the backup files that hold it may have been overwritten and it may be lost for good.
It is very important to appreciate that not all disks are backed up. The disks holding the home directories of all users are, but most experiments also have large data disks and these are not normally included in the backup, because they would flood the backup system. In any case the data they hold are normally also available at other collaborating sites or can be regenerated.
You would be well advised to check within your group as to which disks are protected so that you don't put valuable work at risk.