GST ITC REVERSAL/RECLAIM

Dear experts,

1. After reconciliation of GSTR 2A for the year 2017-18, we found few of our supplier had not filed the return.

2. few of invoice we had not claimed in that particular month.

Now how to reverse/and reclaim the above in GSTR?

is it falling under any rule like in GSTR 3B reversal table rule 42 and 43 or others?

is there any time limit to reclaim and reverse the same?

The same GST reversal and reclaim should be shown in income-tax current liabilities and current assets?

please confirm

thanks in advance.