Im trying to push back in the left or right directions and i press 1 and 2 but it does nothing.. is there a way to fix this? (I havent been here for a while, just if this was posted earlier my apologies, just started FSX-SE not too long ago)

Shift P to start the pushback, then 1 or 2.

 

However, your best bet is to purchase this.  I believe it is worth it for the push back alone.

the classic way doesnt work at all.. When i used FSX with SP2 (deluxe version) when i push back when i would press 1 or 2 (After shift + P) it would do so, now it wont

I agree with Brent GSX is the best current solution, FS2Crew is also working on their own pushback utility. As far as the default pushback goes, I use FSX-SE and the default Shift-P+1 or 2 works for me. The only thing that I have seen where it won't is if you have a addon that takes over the functions of the 1 or 2 keys. ATC addons do this, as well as some others. If that's the case you should remap the keys in that addon if you can, else remap them in FSX itself. It's the Select Item 1 and Select Item 2 buttons under the Simulator control settings.