car wont turn over! please help!!

[midnightsliding]

well the other night i was driving around went to go get some food, came back to the spot where my friend were, cut the car off, when i went to leave the car wouldnt crank, the starter didnt even click, but all my lights worked fine, so me and my friends push started it, cranked up after that, then i dorve off felt fine for about a mile, then the lights went dime, and no power. so we tried pushing agine, it would crank but not run good, so i left it went and got an alternator for it then next day put it on their, pushed it off agine to drive it back to my house, after the push start it drove fine, everything keep voltag, lights worked and car felt normal. so i tought all i needed was a starter now, so went to local auto supply store,, got a starter, put it in, hooked battery back up, and nothing, the starter didnt turn the engine over, or clicked, battery was fully charged, so now im lost and im coming to you guys to see if anyone has had this probel befor!thanks for your helpi need it

[Altiman94]

are you sure the battery is good?

[midnightsliding]

well i tired a friends battery, but it had been siting around in my garge for about 3 weeks