won't start! help

i have a 95 accent that was working fine until one cold winter morning when i tried to start it and it wouldn't start.i checked for spark and there was good spark,i checked for fuel and it was getting fuel.so i thought it must be out of time so i towed it to a garage. a few days later the mechanic tried to start it and it started right away and ran smoothly so he turned it off,but when he went to start it later again it wouldn't start.it's getting fuel,spark and it's in time but still won't start.so has anyone ever had this problem or have any idea what could be wrong? any help or suggestions will be greatly appreciated.