Magix audio cleaning lab isn't very hard to use but isn't free.
I don't want to buy it again so it will be outdated again, hehehe! There's only 1 year free update guarantee anyway
If you have only a few files to fix it's enough to download the trial, free 7 days. 30 days requires free registration.
When done you can uninstall it. (there's another Magix program to uninstall as well).
Audacity have a
Noise Reduction plugin where one have to make a noise profile by selecting a region of the waveform which
contains only noise. However, if the file have much noise everything will be scaled down, even the sound you wanted to hear
better. And what's left of the sound isn't very pleasant to listen to. There's other plugins, filters that I haven't tested.
That's my experience, it depends on how much noise there is. Correct settings and some patience might help.
Read more about Audacity and similar programs at the web page below.
8 Best Free Audio Noise Reduction Software For Windows
Along with a list of freewares there's also some valuable information
http://listoffreeware.com/best-free-aud ... re-windows
listoffreeware.com appears to be safe but...
Some links at listoffreeware.com isn't very safe according to scan reports at URLVoid
I don't know
what to believe anymore, it's up to you.