I want a software which can convert .mp3 to .m4a while maintaining all the tags associated with the mp3 file. Is There any such software?
Here is a link to an audio converter, which converts m4a to mp3: http://www.coolutils.com/Convert-M4A-MP3; you want it the other way round - mp3 to m4a, i guess you can do that using this tool.
Switch Audio Converter
try also Oxelon Media Converter