Presario cq57 wifi - HP Compaq DC7900 Small Form Factor PC Desktop

if not there now
buy wifi+BT card plug it in, the slot
or by BT dongle USB plug it in
most old PCs have no BT .
CQ57 is only series, the number on the end dash - 12345 matter
CQ57-420SE this model came with BT, but there are so many sub models made
and the OS you run now who can guess it works using the wrong OS

you will have to open it up and you will find the coms battery on the motherboard.
why are you after the cmos battery???

Reinstall the wireless driver. go to device manager and expand the device tree. highlight the wireless card and delete. do not check the box to remove the drivers. right click computer at top of the tree and click scan for hardware changes. It will re-find your device and install the drivers. Re-add to the network.

check your bios setting or change the bios battery

Is that a windows or bios pass ?

theres a switch that turns the wifi on/off
if that doesnt work, one of your function keys have a wifi on off switch. so hold function and press the F# key that has the wifi symbol on it

Usually on the Presario models there is a very small button just about the mouse trackpad that will disable and enable the use of it. It's usually between the trackpad and the keyboard

We have several terminals with keyboards that are used by different people during the course of the day. We had a similar problem with the Caps Lock and Num Lock keys. Solution(s): Straighten out a paper clip and make a quarter inch hook at one end. Insert the hook under the offending key(s) and pop it up. You can easily replace the key should there ever be a need. No ham, no foul.

Unplug the router for about 6 minutes. Don't just turn it off. Completely unplug it. Then plug it back in, with your computer on.

You can get a recovery CD from the Compaq/HP WEB site for your model computer.
www.compaq.com/country/cpq_support.html