I am in a somewhat unusual situation so I'm looking for any insights or advice. I graduate with a BA in Economics 4 years ago with a 3.9 GPA. Late in my undergrad career I became interested in computer science but it was too late to do a major or minor, though I did take 3 computer science classes.
2 years ago I took 2 graduate computer science classes as a non-degree student to begin to cover prereqs for a Masters in computer science. I didn't have the prereqs for those 2 but I was overly confident. However I became disinterested in the classes, and fell behind, as well as working full time in a job where I often worked 80 hours a week. I ended up quitting half-way through the classes because I just wasn't committed to whether I even wanted to do the masters at that point, but still got a C and C-.
This past year I decided to get serious about it again, and figured the 2 bad grades wouldn't matter as long as I nailed the remaining prereqs. I took 4 junior level computer science classes this semester and got 2 A's, a B and a C. I was on track for A's in both the B and C classes for the whole semester but screwed up in the last 2 weeks. Now I'm really sad because I feel like a ruined my chances despite having nearly straight A's in undergrad. I want to do the masters at the same school I did my undergrad, which is not really elite but a very good large state school. I would consider other schools as well but I'm worried that I messed up too bad for any decent program.
The reason for posting this is for one, to see if anyone has any ideas on how what chances are for average programs and whether I am overreacting. Secondly, any advice on whether I should try to take more classes before applying to make myself look better? Should I retake the class I got a C in? For more context, I got all A's in undergrad in the 3 computer science classes, 3 semesters of calculus, linear algebra, and 4 statistics/applied statistics classes.