Sir Allahabad ka united college accha hai ya IPS indor aur mai jee me 20 no paya hu to kya dono college me addmison mil skta hai

Sorry to say this is a very poor score in jee mains I don't think you'll be able to get any good college with these marks and even if you managed to get one you might not able to get the core branches. So I would suggest you to either try again next year with better preparation or to wait for spot counseling round but the chances of getting seat through spot counseling totally depends upon your luck and availability of seats.
Good Luck