Its quite common to forget passwords espcially when we don't use that password often. It is the case with router username passwords. Its unlikely that you use the router password on daily basis. If you had changed router's default password and have now forgotten it, here is quick guide for you to recover router username and password.
One of the easiest way is to look for respective router's documentation for default admin username and password. Sometimes, there are labels on the router itself with username and password. We have also developed a list of common username and password here: Default Router Username Password
If you are still stuck because you had already changed default router's username and password. You still do not need to worry, you can perform a factory reset. Once you perform a factory reset default username and password will be restored automatically. Usually a small reset button can be found on router's device, you just need to press the button for one minute for device toma start reset process. You can also consult with the router's documetation to see instructions for factory reset.
This option is only available if your router device supports Universal Plug and Play (UPnP). Using Universal Plug and Play (UPnP) you can forward port without even knowing a password. Usually UPnP PortMapper is used to forward ports. To use this option you need to be a tech savy becuse this option is complicated than others.
Articles
IP Lookup
IP Blacklist Check
Whois Lookup
Proxy Check
DNS Lookup
IP to Hostname lookup
Hostname to IP lookup
User Agent info
Reverse DNS check