My car isn't switching into second gear?

What is your question?

My Buick century 3.3 92 model is not switching into second gear? It happened all at once. It always shifted hard when driving. But now all I can get it to do is go in reverse and 1st??? And even some times it doesn't even stay in first.. it's like it puts it's self in neutral. I changed the transmission module and nothing new... I'm thinking about changing the transmission fluid and transmission filter now? Will that help? Or am I hit??? This is my first car and I love it. Please car people help me..

What makes this problem better or worse?

Dosnt go into second. But it did once when I tryed but I'm scared of messing it up more???

How long has your 1992 Buick Century had this problem?

2 days