my old ipad will not accept updates

Whether you are able to update your iPad to a newer version of iOS/iPadOS will be dictated by your iPad model - and the currently installed version of iOS. You can find this information here:

Settings > General > About

Not sure which iPad you have? Identify your iPad model.

Here is a list of the highest version of iOS supported by the older models of iPad (for simplicity - “generations” are shortened to a number) that are restricted in their ability to be updated:

iPad1 - iOS 5.1.1

iPad2, iPad3 and iPad mini1 - iOS 9.3.5 (WiFi Only models), iOS 9.3.6 (WiFi & Cellular)

iPad4 - iOS 10.3.3 (WiFi Only), iOS 10.3.4 (WiFi & Cellular)

iPad Air1, iPad mini2 and iPad mini3 - iOS 12.5

Newer models, not appearing in this list, are all able to be updated to the current version, iPadOS 14.3.

If your iPad is capable of update, but you are experiencing difficulties, these support pages may be helpful:

Update your iPhone, iPad or iPod touch – Apple Support

If you can't update or restore your iPhone, iPad or iPod touch – Apple Support

If your iPhone, iPad or iPod touch won’t update - Apple Support

If you see an error when you update or restore your iPhone, iPad, or iPod - Apple Support

iOS update and restore errors – Apple Support

To add to what previous posters have posted, you need to understand that your iPad may be obsolete; It will only accept upgrades that are compatible with its hardware.

To see if an upgrade/update is available. open Settings, tap General and tap Software Update. Any update available on your iPad will show there.

If not, you may consider get a new iPad.

It is possible your iPad is too old for any upgrades/updates.

Sorry.

If you need/want an iPad with an up to date iPadOS with access to current, updated apps, then you really need to seriously consider a new iPad model OR a much, MUCH “newer” and less expensive, used iPad models, from better known, trusted Apple product/device retailers/resellers, capable of running the latest iPadOS versions.

There are plenty of newer, older iPad models that can run the latest, current versions of iPadOS.

Sorry & Best of Luck to You!

If you locate what iPad your's is, this(Complete List of iPads, release year and … - Apple Community) will tell you what software it will go to. After that, it will not support any new updates.

What does it say when you try to update it? Does it say there's an update available but it won't let you update or does it not acknowledge that there is any new updates?