Hi, 

With 420 marks you are at a tough spot to get a government college.

According to last years cutoffs:

Government nedical college, Srinagar closed at 456

Government medical college, Jammu closed at 442

Sher-e-kashmir institute of medical science closed at 440

Government dental college Srinagar and Jammu closed at 427 and 435 respectively.

So seeing this trend you chances are less. 

But theres also the fact that cutoffs vary every year. So if this year cut off goes down you might have a chance.

So i suggest wait for the results to be out so that the trend can be seen..untill dn keep ur options open and do check into some private colleges/deemed universities.

Lets hope for the best. 

Best of luck