I have a 6 generation ipad and my battery will not charge

Try any other known good and available spare power/charging cables and Apple power/charging blocks to test whether your current power/charge cables and power/charging blocks are bad/faulty in some manner/fashion.

Apple charging/power cables and power/charging blocks can and do fail, at any time, for any reason.

This is not an uncommon event.

If NO spare power/charging cables and power.charging blocks to test with, you should purchase new USB-C power/charging cables and power/charging adapter blocks from Apple's online Web store or from a nearest, local Apple Store location to test with before scheduling an appointment with your nearest Apple Store location to have your iPad diagnosed and options presented to you.

Best of Luck to You!

The average Apple Battery lasts about 2 years of normal use. I suggest that you make an appointment at the nearest Apple Store for an evaluation and possible new battery.

Apple Store - Find a Store - Apple

An iPad battery is rated to maintain at least 80% of its initial capacity after 1000 full charge/discharge cycles - whereas an iPhone is rated to have 80% of initial capacity after 500 full cycles. Every recharge cycle reduces the maximum charge capacity by just a little - and over time this reduction in capacity will become noticeable. For a regularly used and charged iPad, four years may well equate to an expected battery lifespan.

There are software packages available that can access battery cycle count. Popular choices for Mac are Coconut Battery and iMazing - whereas iMazing is available for PC.

https://www.coconut-flavour.com/coconutbattery/

These support pages should help with troubleshooting battery and charging issues:

Charge and monitor the iPad battery - Apple Support

If your iPad won't charge – Apple Support

Troubleshooting generally requires substitution of the Power Adapter and cable for another known-good item. Most models of iPad require a Power Adapter rated at 12W or greater to reliably charge. 5W Power Adapters intended for older models of iPhone are inadequate to charge an iPad; if the iPad charges at all, charging will be very slow.

Be aware that many computer USB ports cannot source sufficient power to charge an iPad. Unless explicitly designed for charging connected devices, computer USB ports are typically limited to 0.5-1A @5V (i.e., 2.5-5.0W).

If you continue to experience difficulties when using an appropriate Power Adapter of 12W or greater, you might be best advised to seek assistance directly from from Apple Support - and request a remote diagnostic test. You can contact the Support Team using the Get Support link at top-right of this page. Alternatively, you can initiate and manage your support cases using the excellent Apple Support App. If not already installed on your iPad, the App can be downloaded from the App Store:

https://apps.apple.com/gb/app/apple-support/id1130498044

You might also visit the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP) - where the technicians will be able to test and assess your iPad, Power Adapter and cable(s):

Genius Bar Reservation and Apple Support Options - Apple

iPad batteries last long than that!

The batteries in an iPad last longer than those in an iPhone or iPod Touch.

I have a 2015/2016 iPad Pro that I use every single day, for hours, and that battery is still going after 6-7 years!