I can't update my iPad on ios 11 i also don't have any beta plss help me

iPad4 and older models of iPad cannot be updated to iOS11 or later.

If your iPad is currently running, or cannot be updated beyond iOS 10.3.3/4, then have an iPad4.

Update support for iPad4 ended September 2017. The final iOS releases for this model were iOS 10.3.3 (WiFi Only models) and iOS 10.3.4 (WiFi & Cellular). iPad4 cannot be updated to any later major version of iOS as it lacks the minimum hardware requirements needed to run more recent versions. The 32-bit platform upon which the iPad4 is based is effectively obsolete.

iPad2, iPad3 and iPad mini1 are similarly limited in that they can only be updated to iOS 9.3.5 (WiFi Only models) or iOS 9.3.6 (WiFi & Cellular models). Apple ended update support for these models in September 2016. Update support for original first generation iPad ceased at iOS 5.1.1.

Most App Developers have dropped support for older devices and iOS versions preceding iOS11/12/13 - and have withdrawn older versions of their Apps from the Apple App Store. Withdrawal of Apps supporting older models of iPad is making their utility and usefulness significantly more limited. Once compatible versions Apps are withdrawn, you’ll not be able (re)download or (re)install them.

If Apps that you need to use now have higher minimum iOS-version requirements, your only option is to replace your iPad with newer model. If current models, even the entry-level iPad7 supports current iPadOS 13.x and the soon to be released iPadOS14 - and has hardware specifications and capabilities that vastly outperform older models of iPad.

I hope this information is helpful - if only in clearly stating the limitations of your old-model iPad and your available options.

Perhaps your model is too old (hardware incompatible) to support an iOS version newer than the one that's currently running on it. That's why it can't be updated.

Regards

Giulio