Why is all my memery erased?

OH wow this is a bad thing to have a virus or malware erase your hard drive.

You have a few options.

You can take it to a repair shop, have them remove the hard drive and hook to another system. Do a virus scan and get rid of the virus. Then if you want your data back there are several programs that can get the data back, recover your pictures or what have you.

Now option two is deciding if you want your data from the drive or nothing is worth saving. If this is the case then while booting there will be a key to press like F1 or F12 to get you to the recovery console and just reinstall the operating system back to factory and continue with your use of your machine.

A quick search on Google will give you information on how to gain access to the recovery.

Ok so option three would be if in fact you have lost your whole hard drive including the recovery partition. In this case you will have to rely on a friend to get you a operating system the exact one the laptop had, then reinstall your system using the product key stuck on your laptop. I am thinking here it is a before windows 8 or 10 laptop. If a windows 8 or 10 laptop your product key is hidden in the what we will call BIOS and reloading the operating system will activate easily.

Good luck