This is how to fix a pop up sink plug or replace it - to get your bathroom basin working

"If your pop-up sink or bath plug is stuck, this can be because the mechanism that sits below the plug is rusted or broken. It may also be stuck due to a build up of soap scum, debris or mould. Cleaning a pop up plug every few months is one simple solution to keep it working longer."

"In hard water areas limescale from hard water can accumulate around the mechanism, making it harder to operate. Misaligned or bent components, like the pivot rod, can also cause problems. Applying too much force when using the lever can worsen the issue."

Read at Homebuilding & Renovating