I used a Canon PowerShot SX10 IS to take a video. And it wouln't open on my laptop. I made changes to the video like cuttin the beginning on the camera before trying to open it. Is there a way I could open it??

It saids that the file has an extension).THM) that is not recognized by Media Player...then...windows media player cannot play the file.

Try renaming from .thm to .jpg

from Google search:

.THM files are thumbnail images. Typically, these files are identical to JPEGs so go ahead and download the files then try renaming them (replace ".thm" with ".jpg".) Now you should be able to open them in whichever image viewer you normally use.