Check the fuses first, after that you would need a scan tool to retrieve codes stored in the computer of your car (the code stored would indicate where the problem is likely to be). After that you would need to start testing circuits to see if the instrument cluster has failed or lost an input. Hyundai as a car manufacturer put a lot of free technical information and workshop manuals on line for Hyundai owners. Check out www.hmaservice.com lots of great information.
For tachometer not working, the VSS might be umplugged or damaged, or the rear differential was rebuilt.
For check engine light on, generally, the problem is in the emissions or something that is affecting the effectiveness of the emissions, but other causes can trigger the light to come on, too. Besides, some specific causes, such as gas cap left off, not tightened, not installed correctly, or needs to be replaced, engine misfire, and so on.
You can see "Why would check engine light be on" here: http://www.chinasinoy.com/service/why-would-a-check-engine-light-be-on-62.html
But, to determine the cause, you may need a fault code scanner to do some professional diagnosis. Such as elm327, or obdmate om580.
You can see these tool details here: ELM327 http://www.chinasinoy.com/wholesale/elm327-scanner-software-elm-327-usb-plastic-free-shipping-731.html
OBDMATE OM580 http://www.chinasinoy.com/wholesale/high-quality-obdmate-om580-obdii-eobd-code-read-scanner-1356.html
Hope can help you.
Best regards
thanks for your reply. fuses are ok. i used a scan tool and came up with code p0320, "crankshaft engine speed/rpm sensor circuit the engine appears to be running fine. thanks