How can I remove the NextGeeker browser hijacker from Windows?

I would avoid using the PC for purchases or logging into important accounts until it has been cleaned. NextGeeker may only be redirecting searches, but you cannot safely assume that. Grindinsoft is not a tool I would trust just because it appeared in search results. You can download the official Malwarebytes installer on a clean computer, copy it to a USB drive, and install it on the affected PC. If the hijacker keeps interfering, back up only personal documents and photos, then use Windows recovery to reset the PC while keeping your files, or perform a clean Windows installation from a USB installer. A repair shop can do this, but a reset or reinstall is usually cheaper if you are comfortable following the steps.

For a confirmed or uncertain malware infection, the most dependable solution is a clean Windows reinstall rather than trying to chase every browser setting. Create the Windows installation USB on another trusted computer, boot the affected PC from it, and delete the existing Windows installation during setup if you want the cleanest result. Back up carefully first, since anything on the system could be affected. After reinstalling, apply Windows updates, enable the built-in security tools, and reinstall applications only from their official sources. Change important passwords from a separate clean device if you used them on the infected computer.