How do I change the file type of any file? For eg. change from MPEG to MP3, or from TIF to JPEG?
You can only do it with applications that support these formats. In the case of your images, if you have a graphics application that supports TIF and JPEG it should simply be a case of opening the TIF image and selecting the 'SAVE AS' option and select JPEG as the format.
MP3
is an MPEG file. Most people can't grasp this. MP3 simply means MPEG Audio Layer 3. So I don't know what you mean by changing it? Do you have a video clip and want to extract the audio and save it as an MP3? If this is the case, you would need an application that has an extract/export type function that allows you to save the audio only.