1. Try booting up in safe mode and do the following:
a) In command prompt while running as administrator type "sfc /scannow".....without quotes. This will scan and attempt to repair and windows files that are corrupted.
b). Reboot again in safe mode and try running a full virus scan with your antivirus.
c). Now boot up as normal and test your laptop, if still issues, download malwarebytes antimalware and adwcleaner. Update malwarebytes, scan and remove threats, make sure rootkit scan is enabled before scanning and to warn about possible PUP softwares that may be hogging laptop resources. When dealing with PUP one cannot completely advise you without knowing what is installed on your laptop, you must see the results, google if necessary the results found to find out dangerous these and then make a decision to remove them. Run adwcleaner only after running malwarebytes antimalware, with adwcleaner you must be careful since this can both fix and cause certain issues. Google again if unsure.
c) Run "sfc /scannow" again to completely ensure windows is well, if the antivirus and antimalware removed any threats its possible some files will need repairing again.