1994 Ford F-150 about my 94 ford f150 flareside

i was driving down the road an i was in third an went to put it into 4th an herd something when i put it into 4th after that i let out of the clutch to go an it acted like it was in neutral so i tried to put it into 3rd and same thing so i went to 2nd an it went i didnt hear any grinding when i put it into 2nd but i was able to drive truck home using 2nd and 5th gear someone told me i broke a fork in the shifter but how or what is it to replace or fix my problem