How to check loop and it cause in switch and router

[Murad007]

I was facing the issue as we are using 2960G SW and faced some user/VLAN stuck and not pinging with the sub interface in router while we are receiving all mac address then we change the VLAN and interface but the issue was same after that we have hard reset to SW then link is going live so kindly explore the reason of such type issue.and remedy ,please...

[balaji.bandi]

check the logs (if the logging enabled)

show spanning block

show interface status (check any one have errr diabled)