As you have already found, you can't reset the NVRAM1 because your Caps key is in the "locked" state. What this does is add another key to the NVRAM reset sequence making it Command Option P R Caps - this will never work.
However, we do have a solution to get you around the Caps problem...
- Hook up the Windows keyboard
- Boot normally and enter your password
- Disable Caps
- Reset NVRAM from Terminal
- Turn on sharing (optional)
- Most Important - Fix the keyboard
Hook up the Windows keyboard
You said in one of your comments that you have a Windows keyboard. Hook that up because you need a functioning keyboard.
Boot normally and login
To do anything to your machine, we need to get in first and our goal here is to get to a point where we can start working. Use the Windows keyboard you attached in step one, type your login credentials and gain access to the system
Disable Caps
You do this in System Preferences by customizing the modifier keys and setting *Caps Lock * to "No Action".
In System Preferences, select the Keyboard panel

Once you are in the Keyboard panel, click on the Modifier Keys button found near the bottom.

From the dropdown box in the Caps Lock field, choose "No Action." This should now disable your Caps key.

Click Ok to Exit.
Reset NVRAM from the Terminal
From your post, your whole goal was to reset the NVRAM, though you never mentioned why. Resetting your NVRAM will not fix a broken keyboard - it needs to be fixed.
However, to reset your NVRAM, you can do it by issuing the nvram
command.
- Open Terminal
- Issue the command
nvram -c
2
- Reboot your Mac
Your NVRAM is reset.
Turn on Sharing
(This step could also be done when you are disabling your Caps Lock)
I personally like to have a remote access to my Mac for various reasons. One of them being to get in when I don't have access to the keyboard (whether I physically don't have access, or in your case, the keyboard is hosed)
In System Preferences, select the Sharing panel

Have either, the Remote Login (Terminal via SSH) or the Screen Sharing (VNC), or both checked.

Once you have this setup up, you can "remote in" to your Mac to work on it.
Final Steps.. Fix the keyboard
This problem is only going to get worse, not better. Resetting the NVRAM and/or SMC doesn't repair a broken keyboard. Get the keyboard fixed.
1 All Intel based Macs use NVRAM (nonvolatile random-access memory). Apple stopped using PRAM (Parameter RAM) when they switched from the PowerPC architecture. -- How to Reset NVRAM on your Mac
2 From the nvram
man page (man nvram
) The nvram command allows manipulation of firmware NVRAM variables. To get a listing of currently set variables in XML format, issue the command nvram -xp
.