I'm not sure if I posted or not but I'm having a

I'm not sure if I posted or not but I'm having a hard time finding out why my car won't start periodically. I just replaced the battery, 2 days later I get the whiney alternator noise and stall. Few hours later it starts. My clock,a/c setting and trip odometer have been mess up too. They keep resetting themselves. Should I invest in an alternator? No problems today but with my luck I''ll stall in an intersection...Yikes!
Lori