What kind of valve ?? What kind of manifold .. PVC or Copper pipes going to the valve ?

What is wrong with the valve ?

If the valve is not openning or closing AND the cause is NOT the solenoid or the electrical supply to the valve .. or even the controler then :

Option 1 : Rebuild the valve .. replace all the parts except the base which is plumbed into the system and can't be removed without replumbing. Forget trying to replace parts in the valve .. it's a waste of time and energy and money .. simply replace ALL the parts .. EVERYTHING EXCEPT the base of the valve. Just buy a new valve and exchange all the parts .. solenoid .. top .. spring ect..

Option 2 : If the above does not work .. and sometimes it does not then you will need to replace the whole valve and do some replumbing. If replumbing the new valve is not a big deal you may skip option 1.

Good Day ...

I think I'm going to have to replace the whole valve. The valve is a Toro Pro Flo which I understand is not worth trying to fix. Thus, my original question on how to do the replacement since I never replace a valve before. Thanks.

If it is plastic, there will probably be little difference in price between buying rebuild parts and buying a new valve. I would go for a new one no matter what.

Identify exactly which valve you have, flo pro is a start, but you will want to know if it has male or female threads or barbs or both, does it have flow control? Once you have determined exactly which valve you need, go buy it and give it a good examination, take it apart, not much to it and you will see very clearly what a replacement of "parts" entails.

If it is your intent to replace the entire valve you will have to perform some basic irrigation plumbing, not much to it but you might want to visit some of the DIY sites suggested recently in other posts.

I have a Toro Flo Pro valve with quick connect
solenoid.
There is no water coming on and the solenoid is
okay(it works on another valve)
There is a ring at the top of the valve which I think
is the flo control
I cannot turn it counterclock more than 5 mm. On
another similar valve I can turn this flo control 2-3
turns and more counter clock.
How do I clean the flo control?
Can I just attempt to force it?
KS

I guess you should already have a solution by now with all of the above very comprehensive replies. They are very beneficial for me too in case I should ever need to replace my valve. I agree with you that valves are not a common problem, that is why it becomes kind of tough to get a specific answer to your type of question. What I know is just to ensure that the water supply has to be turned off first prior to any piping or waterworks just to be safe.

You are correct in your earlier statement about the Toro Flo Pro valve. Probably one of the worst and most unreliable valves put out by Toro. I would replace it.