There are lots of lists of suggested free software on the Interweb. This is my version. It's just a list of stuff that I've used for a long time and usually install on any new PC that I set up, repair or refurbish.

7-Zip - My favourite file zipper, unzipper, archiver, etc.

Audacity - An amazing audio editor. Takes a bit of learning.

Bulk Rename Utility - If you need to rename lots of files in one go, this is the tool.

CCleaner - Tidy up your files and get rid of accumulated junk.

Defraggler - Defragment your hard drives (not for SSDs).

FreeFileSync - If you need to sync two drives for backups, this is the tool for the job.

Exact Audio Copy - The best CD ripper.

Firefox - My web browser of choice.

LibreOffice - The best of the free office suites.

MP3tag - The best MP3 tag/filename editor I've found.

MusicBee - My favourite music organiser & player.

Notepad ++ - It's like Notepad on steroids.

Thunderbird - My favourite email client.

VLC - The ultimate video player. It does lots more too.

Kdenlive - Excellent video editor. Takes a bit of learning to get the best from it.

Crystal Disk Mark/Crystal Disk Info - Hard Drive testing and speed testing software.