Hello and welcome to justanswer, My name is ***** ***** i will be assisting you today
What is your operating system (windows or mac) and What is the type of the file you want to convert ?
Please use this software to convert your files : http://www.mediafire.com/download/547c4roamc1bbcc/video+convert.rar
Once you download the software, please run it, select the file you want to convert and the type of format you want to use then click convert.
Try to convert it to MOV or MPEG.