Is it possible to to fix a crash on my mac os x 10.4.11 without using or having to buy a new installation disk?

I know this question has been asked so many times but i will tell you all about my mac and its problem. My oldest sister was in alaska and she bought an Apple ibook (either G3 or G4 i really dont know) on ebay for my second oldest sister. about a year later my sister gave the laptop to me. the software version is mac os x 10.4.11. anyways after about a week of messing around on the mac it crashed. i have been online so many times trying to find a solution. i am still able to get on my laptop but all the headings for stuff is blank. the date will not show and some of the applications will close after a few seconds after opening it. if i try to click on the mac simbal on the top left of the screen the headings for the options will be all blank, it is the same with all the other things on the menu bar thing. even all the error codes are blank. plzz i dont care if it is illigle or not could you please tell me or give me a hint on how i can fix the crash for free or restore the system without a cd. because when my sister bought the laptop off of ebay it did not come with a disk. could somebody plz tell me what is wrong with my mac or at least give me a clue on how i could fix my laptop for free. dont tell me what u have told other peoplez if i have to go out and bye somthing to fix my mac, i have seen alot of questions or pleeds for help and alot of them dont get an answer, if u dont have an answer for me spread my question around because i really want this thing up and running correctly...........thanks