Changing settings on my AC1600 wifi cable modem router without being conected on a wifi device?

> dont know what to type here

   How about a clear explanation of what you did, and what happened when
you did it?

> need to know how to get into netgear wizard to change stuff from my desk
> top [...]

   Use a web browser?  What is your "my desk top"?

> keep getting page saying you must be on wireless device to acsess.

   When you do what, exactly?

   Are you getting the page which says, "You are not connected to your
Router's WiFi network. [...]"?  If so, then welcome to what may be the
worst error message in the world.  For an explanation, try:

      https://community.netgear.com/t5/x/x/m-p/1365830

   Briefly, the idea is that "[www.]routerlogin.net" should point to
your own router, but that's true only if you use your own router for DNS
name resolution.  Irregardful, you should be able to get to the thing
using its IP address, if you can determine (or guess) that.

   "AC1600" is a speed, not a model number.  Ever helpful, Netgear
product packaging emphasizes speeds like "ACxxxx", but that's not the
model identifier.  Look at the label.

   The User Manual for your router should tell you what its default LAN
IP address is.  Look for "192.168.".  Otherwise, you can often get it
from your (unspecified) computer's IP configuration as the default
gateway or router address (or some similar description).  Visit
http://netgear.com/support , put in your (actual) model number, and look
for Documentation.