Why is my MacBook Pro running so slow?

Question

I have a MacBook Pro that I bought in September 2012, and it has been running absolutely fine until last week. I left it on for an hour while I went out, and when I came back it was suddenly running really slow (couldn't get rid of the spinning beach ball of death). I thought maybe it was because it needed updating, so I attempted to do this. However, it didn't do it properly. Not quite sure what happened but then it wouldn't even get past the startup screen. I know it's my own stupid fault that all this has happened, I kept ignoring the 'updates available' banner. Anyway, I googled what to do and got so impatient, I tried resetting the PRAM, verifying disk permissions, fsck, checked activity monitor etc. Nothing was wrong or out of the ordinary. I reinstalled OS X, took 24 hours but for some reason still wasn't working. So I tried it again, still didn't fix it and was stuck on the startup screen. Not quite sure what happened but then it eventually came on, although sadly somewhere along the way I had completely wiped my hard drive. Again, I was stupid for not backing up my data, and should have just left everything to the experts rather than being so impatient. After all of that, I've installed mavericks but it is still no better. It is just as slow as when it first started playing up, although at least it is actually functioning on some level now. I've accepted that I'm never getting my data back (unless anyone can tell me if there's a way?), but I'm baffled as to why it still isn't working properly, and I have lost everything for no reason. Please can someone help me as I am ready for throwing my laptop at someone or something.

Answer 1

chunk1234,
if your lost data is of considerable value to you, then you could try hiring a data recovery service, but their time is expensive. If you wish to go down that route, cleanly shut down your MacBook Pro, and don’t turn it on again until after the data recovery service has returned it to you — every time you do something on your hard drive, you make it more difficult for data recovery to succeed.
You might want to buy an external hard drive for use as a Time Machine backup destination, so that this situation doesn’t happen again — restoring from your last backup is far, far cheaper than hiring a data recovery service.
Regarding your current slowdown, have you tried resetting your MacBook Pro’s System Management Controller?