Push open basin waste - wedged closed

[mypinkmonkey]

Any advice please for how to release a basin waste which has been wedged down. It normally pops up easily but someone has pushed it down too hard. I have removed the pipe underneath and tried to push it up from below but that hasn't worked. I have also tried using a plunger but to no avail! TIA.

If it's a pop-up waste, I'd try levering it up, then when it is up, unscrew it (using a monkey wrench, the top disc will unscrew) and then clean off any gunk and liberally wd40 the mechanism. Worked for ours!

you can with (strong fingers) turn the plug section anti-clockwise. Once its loose it will pop back up. Then wd40 as suggested. Try this first as you'll be less likely to damage the sink or yourself!