The good news is that your data is not completely lost, only some of it will be gone from your phone's reading time. However, since most users set their Safari to read everything within a few seconds, the information is essentially gone forever. This is why many people recommend that you do something before your device goes into read-only mode, such as performing a automatic backups of everything that you have worked on so far. These backups should be performed every day at least once, though.
It is advisable, though, to perform an automatic backup every day, since you don't want to go wrong. If you still need to retrieve contacts or any other data, you can do so in this manner, too. To retrieve contacts, you can do this by going to'myphonesphoners'. From there, you can either click on the name or address to get the contact list back, or you can use the search feature to try to find the person. In case you've deleted an entire contact list, you'll have to go to the device's storage and retrieve all the backups for it.