Please help me, I have a very important vedio and when I opened it on the computer I discovered that the file is a lock file and it won't open :( how can I open it? Thank you a lot

Reboot and try again.

What is the full name of the file. What is telling you it's a lock file? Did you ask the source of the file to send again?

Sometimes these are files obtained by bittorrent and they force you to do to a website to get the "key". Once at the website your computer will be under attack from malware.

VID 00031-20120829-2111.3GP.lock this is the full file name, and when I try to open it, it won't open, what do you mean by asking the source of the file to send again? I tired many things I sent it from my mobile to my laptop many times and I tried to download players for it and it just won't open :( I hope you have the solution, ps:- the vedio was recorded on blackberry curve 8520

So you recorded the video on your Blackberry? And then sent it to your PC? In that case you need to check with Blackberry support on how to transfer videos to a PC.