Take backup
iptables-save > ~/iptables-`date +%Y%m%d_%H%M%S`.bak
Flush now
iptables -F iptables -X iptables -t nat -F iptables -t nat -X iptables -t mangle -F iptables -t mangle -X iptables -P INPUT ACCEPT iptables -P FORWARD ACCEPT iptables -P OUTPUT ACCEPT
Again to restore from backup
iptables-restore < bak.file