you need to see if the collar"will come off, it may screw off , or there may be a screw holding the collar on , all the collar is doing is open a way for the water to the taps or shower,and the bar that it pulls up is stuck, you need to get a pliers, and pull the bar thats under the collar up and down untill it works as normal, and then put the collar back on , have the cold tap running when your working on this, try this first,,
p
March 2011