Heated towel rail is cold

I turned the central heating on tonight for the first time since the Spring but the towel rail in my bathroom won't heat up. I must have turned the rail off a couple of weeks ago, when I attempted to add inhibitor. After trying to follow an online video on how to add inhibitor I gave up and thought I'd reversed the actions but I've clearly missed something as it now won't heat up. I'm sure it's just one simple step I've overlooked. Can anyone help?Thanks.

 

Open both valves fully on the towel rail (anti- clockwise).
If one of the valves is thermostatic (trv), then you need to check the pin on the valve body hasn’t seized.
Check if any air in towel rail by bleeding it.
Next turn most of system rads off and run heating for a short while to see if towel rail heats.

 

As above ^^ it will be one of those.

 

All working again! Many thanks for your help.

 

Air lock?

 

Completely agree about air in towel rail. I had similar problem and couldn't find this way for a long time