there are 3 ways to do it. you can check through the command prompt as an administrator and for a full system scan type in MpCmdRun.exe -Scan -ScanType 2
for a boot sector scan type in MpCmdRun.exe -Scan -ScanType -BootSectorScan
hit enter for both commands and you will need to look through the scan reports on the command prompt.
if you don't want to go through that then you can download Malwarebytes to run additional scans for malware. I also recommend activating safe mode until the computer is no longer under threat.