|For someone to access your computer you need to have files and print sharing active and they can access only files or folders that you designate as share (unless you made the mistake of 'sharing' your entire hard drive).|
First, protect your computer with a password both for logging on and for waking up.
Second, Run Malwarebytes to make sure that someone did not install anything to give them specific access.
Third, make sure that Remote Access is disabled so they cannot access your system from another computer.
Depending on your level of trust, the required level of security, and the tech level of other people in the house, others may have other suggestions.
You have to be a little bit crazy to keep you from going insane.