@Gopinath R Check your KYC, is it updated.
Demat holder name / PAN should match with Bank account holder name/ PAN.
Check the e mail of Ragistrar, whether it is showing rejected/ non allotment due to over subscription.
Normally if rejected, amount will get unblocked before allotment.
Lastly, wait for an under subscribed IPO, take risk, apply in it. Pl note, if alloted here, may get discount listing.
If all ok, rely on your luck.