check out this link: https://forums.linuxmint.com/viewtopic.php?t=228054

What solved the issue was to reset the BIOS settings, not sure if it will work for you.

Browse to the end of the page on that link to see the solution.

it looks like there are some pre-set keyboard shortcuts that you can check in case one might activate/deactivate your wireless.

another possibility to consider would be different keyboard layouts (also from the user manual):

my two computers with xfce both have several dell options to choose from. none are vostro specific, but one of those might give you access (or trying 104 instead of 105 key) might give you access to the fn keys.

Thanks but I tried that and no change.

Do I need to reboot every time I change keyboard layouts in order for them to take effect?

Also, how do I get to the xfce4 start page? The terminal tells me that ~/.config/xfce4/xfconf/xfce-perchannel-xml/ is a directory; what file in it has the channel names, and how do I open it? This is all new to me.

the user manual (p25) doesn't mention anything about needing to reboot between layout changes. i have never had the need to do change mine so can't say from experience. if nothing seems to change, you might want to try a reboot just in case.

for the record on my xfce machines (neither are mx so yours may differ) the option is under a "layout" tab, but the dell choices would be under keyboard model.

it was linked through the previous link i shared. i don't see anything particularly helpful there, but it might be worth a look-see.

page 26 of the user manual mentions that there is a section of keyboard settings that shows you (i think only some of, but probably the more relevant) the application shortcuts like alt + f1 opens the user manual. the keyboard shortcuts on my systems are listed in the xfce4-keyboard-shortcuts.xml file. you should be able to double-click the file to open it. on one of my machines it opens with a notepad program, the other with firefox. or you should also be able to right-click and choose whichever you prefer.

in general my keyboard shortcuts are similar to those listed in the mx user manual. the others listed in the xml file mostly deal with switching workspaces which won't be of any help to your situation.

Thanks for all the effort. Since Dell shipped that model with the option of Ubuntu 8 installed, I D/L'd and installed a copy. The wi-fi didn't work and neither did some other vital functions. Just for grins I tried Ubuntu 20. Presto, the wi-fi started working, and it's been like happily ever after.