Signs that someone has been tampering with your computer could be very subtle. You might have noticed a suspicious program that is suddenly running, weird messages are constantly popping up, or your PC might just not be running as it should. Some tampering may not be detected at all, such as certain keylogger apps that are designed to be running quietly in the background without your notice. A keylogger records everything you type and sends it on to another person, compromising your privacy and security, so the sooner you get rid of it, the better.
Secure Your Hardware
If you suspect that someone has been tampering with your hardware, get a case with a lock and chassis alarm. Lock the front door of your computer case every time you leave the room to ensure nobody can switch the PC on or plug in other devices. Check your keyboard wire for any extra device. Hardware keyloggers are usually inserted in between your keyboard and the PC, to record your keystrokes directly.
Run an Anti-virus and Malware Scanner
Check whether your Windows firewall is still switched on.You can find these settings using the search box in Windows 8 and type "firewall." Tap "Settings" and select "Windows Firewall." Ensure that your anti-virus is up to date and do a full scan to search for any malicious software that might have been installed. It is also advisable to install software that searches specifically for malware, such as Malwarebytes or Spybot.