How to arrange an out of warranty repair on you Dell computer  https://www.dell.com/support/kbdoc/en-us/000132374/how-to-arrange-an-out-of-warranty-repair-on-your-dell-system

How to contact Dell through multiple channels  https://www.dell.com/community/en/conversations/customer-care/how-to-contact-dell-through-multiple-channels/647f902df4ccf8a8de1630f9

I doubt Dell will have parts for a system this old -- the keyboards are under $50 and any local computer shop can replace the keyboard for you for whatever an hour's labor costs in your area.

https://www.parts-people.com/index.php?action=category&id=143&subid=517&refine=keyboard