That's because your account is probably deactivated. P2S is very strict with one thing. Only one account can be used on a single computer. Can't log in on a friend's computer, using wi-fi in a public place, nothing. They don't want people 'stealing' from them. AKA having multiple accounts to do the same offers that are easy and give the most points. What you can do is send in a ticket saying either an apology/something. It happened to me, and I told them I would never log in on my friend's computer again, and vice versa. If they see two I.P's for the same account, you're done. All you can do is send a ticket asking for them to open your account again. Other than that, you can't do anything.
And to get points in general, yeah go to the main offers list. If the offer is too long it probably isn't worth it. I usually do a bunch of 30-40 points ones where all you have to do is register. I also do some 50-100 point ones where it's just a short survey. You just gotta be good at finding them, and then it will be so easy to get a ton of points.
