What is wifi - Computers & Internet

2004 , made, 15 years old PC, a BLAST fromt the PAST!
now"? so , yesterday you had wifi and today not?
are you at home or in a Cafe' or airport, where are you.
first is does your location have wifi.... (and distance to the AP)
AP is your local Access Point (at home a router with wifi)
also as important is the A400 is a very old desktop Tower.
and as such most had no wifi ,unless you added it.
on the rear is wifi card (PCI) with an antenna, if said antenna or car is missing then bingo no wifi.. see here ,? no wifi, just a silly old dial up modem there.
proof:
https://www.cnet.com/products/hp-pavilion-a400n-c-2-7-ghz-monitor-none-series/


on this PC you have 2 choices.
buy the pci card wifi plug it in
or buy USB wifi dongle.

you posted with NO OS,
is it windows?
if yes, what version
it came with windows XP is this the last XP running on earth?
XP is and its very bad IE6 is now banned on the internet.

I'll give you some help on ANDROID. Go to apps, settings\ WiFi. Turn it on at top of screen. Any available WiFi accounts will show up. Then go to top right push the three dots, click advanced and make your choices. Click back to WiFi screen and click the WiFi you want to connect with, enter the key that your WiFi needs to connect, or use the WPS option if available on you WiFi. If the WiFi has WPS, push the button on the WiFi and connect your tablet or phone by pressing connect.

check if your wifi from BIOS is turned on or off.

Is the wifi enabled, can you see any wifi networks? If not, make sure wifi is enabled, if there is button on laptop to disable/enable wifi connections, swich wifi on.

Check from control panel -> network (network and sharing center in Vista/Win7) -> change adapter settings. If wireless lan adapter disabled (grayed out).

If nothing pop up on Task bar even after pressing the WIFI button so might be the WIFI drivers are missing... so install WIFI drivers and check it...

"Problem with Cradlepoint CBR450 Compact Broadband Router without WiFI"

it does not support WIFI will need to get one that does support WIFI to connect that way.

Goto your phone connection settings:-

Select -> Wifi -> On.

Search any Wifi Network and Connect..

1) check if your wifi is turned on.
2) reinstall the wifi driver.

sorry not able to get wifi if the Phone has wifi features means,you can call the service provider and get the wifi settings and get the wifi if the Phone has wifi feature means....