Water Heaters - Water heater valve

For reasons I won't get into I opened the drain valve on my water heater and now it doesn't shut off completely. Has a continous drip. Can I replace that valve or do something to make it stop dripping?

Yes if your not handy pick up a boiler cap and screw it on to the end. In a pinch you could also use a hose spayer is the vale brass or plastic ??? The vale can be replaced you can do it on the fly but you have to be real fast . to do this turn off water to tank open vale when water stopes coming out close vale un screw and replace water will glug out if you are not fast or vale breaks you will emty tank been there done that what a mess.or kill the power and flush the tank and drain it.

I vote for a simple "hose bib" cap. Simply screw it on the exposed threads.