No sound on videos!

Hello, i have a hp laptop its new and everything, but once i have uploaded my videos off my phone onto it no sound is on them! i am using the windoes video player and it says that there is audio playing, but i am hearing nothing! on everything else like internet and itunes and dvds i have sound, its just when i want to watch my own videos! i'd really apreciate some help, thank you! [: x