Connected to net, but safari wont open? work?

Greetings, I am new to mac, but ive had an iphone for a while, and I have some linux expierence. I recently brought a friends macbook pro (coreI5).

Here is the problem I am having:
I CAN connect to the internet, via wireless or wired. (Presently im wireless)
I CAN connect to itunes, but not app store.

I can not get safari to open. On my dock, where the safari icon would be- is just a grey question mark that is named safari.

Here is how I may have gotten to the problem.
It connected to the internet just fine last night, safari was opening, etc.. However, because I got this from my friend- i wanted to be sure that i essentially wiped all of his stuff- personal and other- off. SO what I did that MAY? have caused the problem

a )I got the password from my friend
b) created another administrator account
c) logged into the other administrator account
d) deleted my friends account (which was also administrator) Not only did i do the simple removal (i seem to remember it gives you three options) I chose the MOST complete option- dont remember what its called

Now that Ive done this- I have the problem... I have 4 bars on the wireless thingy, but I cant get a browser to open..

Im guessing maybe safari got axed when i wiped my friends admin account, leaving just mine?

do i need to go to terminal and do some sudo-aptget thingy? (if so- whats the exact line and such?

Thanks

P.s I did try to meander through other posts, but seems the others are more for a problem i dont have?

and, maybe this would help, but how do i essentially reset it to day 1, so it thinks that this is the first time anyones ever used it, or some such?