Conversion between various video & audio formats

[Ada]

Could anyone advise me a good software to do conversion between any video &
audio formats?

I have used "Total viedo convertor" to convert a .wma file into various
viedo formats (.mpg, .flv, .avi), but none of them can be posted to Facebook
or Youtube (the latter 3 viedo formats should be acceptable to Facebook &
Youtube). I guess the failure is due to the source file is an audio file &
convered into a viedo file, not a conversion from 1 viedo format to another
viedo format. Could anyone kindly advise?

Many thanks!