ok my car is at home sick!
i got a 2003 mazda protege5, but i think this is a every car question.

for a few mounths my car has been slowly having a harder time of getting into drive first thing in the morning(auto stick car). but friday it made a clunk and 45mph and down shifted it will only let me go into 1 and 2nd. lucky it will go fast enogh in 2 to get me home with out getting ran over. but after spend most of the day call shops i'm thinking its the shift solenoid, or the pack of them or what ever. what are the signs that its was going bad in the first place?

so! my question is dose this sound about right or can it be something else? and how much and how hard is it to change my self or am im better off just takeing it to a shop? the cars has 170k miles on it and never really gave me any problem other then a bearing that needs to be replaced to.(money and time) any help thanks guys