Walk
Memory sticks (called RAM) do not 'hold' any data at all UNLESS they are currently plugged into your computer's motherboard and the computer is ON (or booted up). They only store stuff on a temporary basis and everything on them gets erased each time the computer is shut off.
The stuff that is "saved" is permanently stored on the computer's hard disc drive. The hard drive keeps EVERYTHING (some of the stuff that gets 'saved' may not be accessible to you)...AND everything will remain on the HD unless you delete something...(****Note that even if you delete stuff or put it in the Recycle Bin, it still remains on your hard drive [somewhere hidden]...and normally you can't regain access to deleted files).
The stuff that's 'saved' on the HD includes the operating system with it's files and folders (Win 7 or Win 10 etc.)
...It also stores all the programs that came with the computer - like a text program, a spreadsheet program, etc. and game programs like solitaire.
...it stores a browser program (Internet Explorer) that allows you to access other computers that are connected to the internet - some of those computers 'store' web pages like iHub. Generally, a browser program lets you "surf the web".
...The HD stores any other programs you may have downloaded from the internet. It also will store malignant virus programs and Trojan programs that can mess up your browser operation and-or your operating system program.
So, a very good computer expert can figure out how to get rid of viruses or Trojans if they caused the problems...He can retrieve missing shortcuts or repair inadvertently hidden files...he can restore your machine back to proper operation...
That is he can "put it back to the way it ran before you started having problems".
****Note That's why when the Hildabeast said she erased or wiped all unrelated emails from her basement home server, the FBI's computer experts were able to restore many of them.