Free help ASAP during the holidays! LOL, only at Tom's is that even conceivable.
Your description is a bit lacking, but I will assume that the Westell is the modem and "main" router (that I will refer to as a gateway since it is both). The other two units are simple routers that were likely configured as WAPs (wireless access points) and connected to the Westell with either an Ethernet cable or sets of powerline adapter.
Not sure where the other stuff (switch and other AP were connected) but a hand drawn network diagram would be illuminating.
How bad did your daughter screw this up? In other words, what still works and what doesn't?
The bottom line is that the gateway (Westell) should be the only device on your network that has DHCP enabled (assuming that you have a single network and not a series of subnets). The other two routers should have DHCP disabled, have static addresses that are in the network range but outside the Westell DHCP assignment range, and should use different non-overlapping 2.4GHz radio channels, and should be connected LAN port to LAN port. The only WAN port connection would be the DSL line to the Westell.
Is this anywhere near what you have configured, since there are many ways to do these things?
And please restrict yourself to one post per topic in compliance with forum rules, more posts on the same topic really don't get a quicker answer.