Keyboard keys not working

This is a hardware failure which cannot be solved by tinkering with software or drivers.

How do we know it's a hardware failure?

Because the keys all failed in the same area. This points to underlying, common circuitry that has failed. It is not the behaviour of failed drivers. Note that the OP didn't report spilling anything or keys sticking.

Sure, take a couple of minutes to go into the BIOS to confirm the keys don't work even outside Windows if you have any doubts. But really, your focus should be heading over to eBay to buy a replacement keyboard for $15.99. (That is all it costs).

Ignore suggestions of taking it to a professional to be cleaned. Will that cost a lot more than $15.99? Yes. Does it stand a CHANCE of fixing your keyboard's hardware problem? No. Literally zero chance, because the problem is not that it is dirty in the first place.

If you are not sure how to install the replacement keyboard in your Compaq 610, you can ask a tech-savvy friend to do it for you. Alternatively, if you want to try yourself, take a look at some tutorials for laptop keyboard replacements to give you some idea. I did my first one when I was 18 in 20 minutes, just using a PDF user guide. It's even easier now there are videos like this out there:

http://www.youtube.com/watch?v=CRpvWq7C8U4

Good luck!

Keyboards have issues, so in case some keys don't work , i can only tell you a way around

Instead of using on screen keyboard, You can use key mapping to allocate the funtionality of those keys which are not working to those which are working for example you can set the ESC key as left SHIFT key ----

Here is a link which recommends a great Key Mapper "Sharp Keys" and tutorial with screen shots on how to map the keys -

It's probably hardware issue because not responding buttons are in same colon. First try with different OS. If it works try updating or rollback drivers. Also run sfc /scannow in admin command prompt. If it doesn't work, try this link.

EDIT: Here is very good answer.