Why does my iPhone wont charge after I left it drained for 2 days?

I agree with Andrew's answer, try a known good charging cable and wall charger first.

If that does not work then it's probably best you take it to a mobile phone shop that does micro-soldering / board level repairs for troubleshooting because this issue can be caused by many things:

- Bad Battery

- Charging Port

- Or at worst a bad charging chip which would require micro-soldering to replace it.

To do it yourself you will have to start off with trying another charging port, especially test with battery unplugged and charger plugged in, if you don't get apple logo on at this point, and with a replacement charging port assembly then the fault is most likely caused by a bad charging chip. It will cost a fair bit to buy parts just for testing.

Wood tooth pick try to pick out any foreign junk out of charge port they often get a build up of dirt n dust and hair that stops charging

A lot of the time, iPhones that won’t charge can be fixed by taking a toothbrush (that you’ve never used before) and brushing out the port. You’d be amazed by how much lint and gunk can accumulate in there! Make sure you also try another outlet. This website has a more complete guide about what to do when an iPhone won’t charge, but although you can fix a lot of problems at home, sometimes you just need to get your iPhone repaired... or do it yourself with the help of iFixit!