I love sharing money saving DIY fixes and projects. If your tub won’t drain during use first make sure it’s not clogged. My lever wouldn’t stay in a down position without holding it down in order for it to drain. You should be able to find a repair/replacement kit at any hardware store for your tub lever.
I am not a professional everything I do on here is a first time attempt. I try to show easy ways to complete DIY home improvements and typically without buying extra tools you may not ever use again.