Why won't my xbox read the game?

Try cleaning the laser lens with this:
http://www.gamestop.com/xbox-360/accessories/xbox-360-cleandr-laser-lens-cleaner/93068

You have probably downloaded some DLC (DownLoadable Content) and it might have been deleted, so you have to re-download it to continue playing the game.

It is probably scratched, or have became dirty, unless there might be a problem with the xbox laser-reader.

Try with other games, and if there is the same problems, it might be the laser-reader.

If it might be the laser-reader, you should try ejecting the disc tray, remove the disc if there is one, and try to blow "downward", because there might be dust on the reader, which can give the xbox problems with reading discs.

I have had similar issues with Saints Row 2, the best fix that I have found is at the main dashboard menu go over to settings> memory and highlight your hard drive or other primary storage location and press "Y" choose the option to clear system cache. Hopefully that will work for you.

did u get the respect points

Try updating your Xbox 360 console on Xbox Live with the game inside the disctray. Once you join Xbox Live it will automatically prompt you for an update, all you need to do is to confirm.

try and save the game to your Xbox360 harddrive(HDD) and then run it off that?

i have no clue im a big fan of saints row i can tell you any ather thing about the game

clean the lens on ur xbox.. buy a lens cleaner disk from almost any electronic store.

Well the disc driver obviously works on most of your games except saints row 2. Saints row 2 is in mint condition well i have this problem too with my 360 it reads some games and it doesn't read my other ones well theirs a few ways one is by leaving the game inside of the console and shut it down wait like 5 seconds and turn it back on.
Another is to make sure the laser its self doesn't have dust on it.
And when you put in a disc listen to it as it spins if makes any weird scratching noise its probably the laser hitting the disc a lot of 360s disc have been getting scratched recently due to the fact in microsoft's original design of the disc drive the laser keeps on hitting the disc and scratching it so if thats the case you have to replace the disc drive.
If solutions don't help let me know i might be able to help you more.