i got 73 narks in jee mains obc catagory what can i do next iam clueless can someone help me pls

I'm afraid you won't be getting into a NIT with the marks you mentioned . Though you have a chance under home state quota for the colleges located in your state (where rank cut off could be high or low depending on the states).
Other option is to go for NIT in eastern states
Otherwise you can go for some of the renowned private colleges like thapar or VIT.

Definitely. If your from a reserved category , this is not that good. Sometimes you can get some state nit like tiruchipalli, durgapur with thus rank , but you would have to wait for the last round if counselling. You can also get an nit from state quota.Don`t worry you can get a good government college. Go for some college predictors available online.All the very best!!