Need replacement DVD in 2005 Discovery

Yes, replace it with a Blu-ray player as it will really improve the picture quality on your TV.

you can replace it with any DVD/Bluray player you want

but you WILL find yourself doing some cable re-arranging , since most new models do NOT have RF or composite A/V output
being HDMI and Component only outputs

For simplicity, you may try looking for the exact same model for sale on eBay. This would give you back your DVD with all of the wires being exactly the same.

I probably have the same one in my 05 Expedition. Are you still using the box of buttons to switch between devices? HD?

I got rid of the box of buttons, installed a flat screen HDTV, ran HDMI to the tv from the sat box, Bluray, connected the ant directly to the tv ran a sound cable to the Surround amp (TV input) now I use the tv input selector to switch between sources.

Now when you switch sources sound comes out of the surround amp no changing inputs required.