i´ve had this problem too.
what happened to my car was that at first i could drive the car in 1st, 3rd and 5th gear, and reverse. okay.. then it stopped working at all ...
i would suggest that you fix it asap or if you cant do it yourself, take it to a mechanic. it shouldnt be so expensive to fix.
a tip: if you are driving around in it and it wont go into any gear you can open the hood, and on the right side, beside the engine there is a "L" shaped stick... (make shure your car isnt on and shifter is in neutral) you can push or pull this lever / stick back and front.. until it goes into gear, you should feel it when it pops into the gear, otherwise you can always start the car and try to drive off. you can do this a few times untl you find the 1st or 3rd gear.. 1st gear is better of course but you can also drive it in 3rd but its not very popular with your clutch. but.. try go get it into 1st and drive sowly home or to the mechanic.
i had this thing fixed on my car.. and shifting actually got better than before i had this problem..