.Rar Files Downloaded But Are Now Showing as .HTML

When I was downloading them they were showing as .rar files but now in my download folder they are showing as .html files but the same size as the fully downloaded rars. When I try to click on them it freezes my pc for a minute or so.
This happened yesterday with half of the files for something else but after a restart they were showing as rars again, tried doing that this time but its not worked. Has anyone got any ideas?
Answer #1
Just rename the .html to .rar and then extract them
Answer #2
Got it sorted thanks, just had to choose the program to extract them and wait while my pc froze
Answer #3
Rename it to rar and open and extract like normal