My game gets jammed just after the fifth chapter.Can someone help me?

What do you mean 'gets jammed' ?
There were times when my game would seem to glitch, my guy would run in place and the screen would boggle (and my disc is in mint condition)
See if you can pick up a used copy for cheap! You may have a defective disc..

Well try cleaning off your disk, then if that doesn't work, maybe find the chaet to unlock all the missions so you can still play without buying a new one.

Your game might be dirty or glitched.

If it's dirty, then it should work just fine once you clean it.

If it's glitched, then it's probably not gonna work period.

Hopefully it's just dirty.

Hope your game is fine. :D

Assuming you have a PS2 version, how old is your console? If it's a few years old it may be getting ready for the dreaded DRE defect. I have another game (toca race driver 2) that constantly locks up after a certain level and won't let me proceed, my console is older and is starting to DRE on certain discs, pretty sure that's the culprit, so yours may be doing the same. As said it may be just a dirty disc, if not a console going bad has the same symptoms. You can clean the laser but that is a stop gap fix, they go bad in time.