GST LIABILITY MISTAKENLY PAID THROUGH CASH

Hello,

I had GST Liability of 6 lacs and I was having GST input credit of 6 lacs.

But while filing GSTR 3B, I have mistakenly paid 6 Lacs liability with cash balance and the GST input credit of 6 lacs is being idle in GST input credit ledger.

As it is not possible to revise GSTR 3B and I don't have any further business to utilize that credit.

How can I get back that Input credit of 6 Lacs