How do I configure my router when I disabled port 80?

So I don't understand back-end website creation. I wanted to, for a day or two, port forward port 80 on my router to a raspberry pi so I could try out making a website accessible through a public IP, as a learning experience (I know this is unsafe so there is some security in place and it will only be open for a short time) I was configuring my router settings through a web browser and I found out that I couldn't use port 80 for the public IP (because it was how you accessed the router config site). I went into the settings and disabled HTML access through port 80, which, quite obviously in hindsight, made me lose access to the router. I have access through FTP, ICMP, SAMBA, SNMP, SSH, TELNET, and TFTP but I don't know how to use them. Any help?