I got a 2100 PSAT, but when I took the SAT for the first time I got a 1970?

I got a 2100 PSAT, but when I took the SAT for the first time I got a 1970? Why did I get such a low score? I know I did especially bad on the writing section, even though I got a 10/12 on the Essay, I just really screwed up the sentence corrections. Is there any way to bring it back up to my PSAT score? Thanks