Links:
Diagnostic:
Core Temp
CPU-Z
GPU-Z
Crystal Disk Info
OCCT
Cleaning:
Wise Disk Cleaner
Wise Registry Cleaner
Repairing:
Try SFC /scannow from CMD.
Graphics editor:
Krita
GIMP
Paint.Net
Text editor:
LibreOffice
AbiWord
Notepad++
Anti-virus:
Malwarebytes
Comodo Internet Security
Kaspersky Security Cloud – Free
VirusTotal