How to find whether button is disabled or not in Selenium IDE

You can use VerifyNotEditable to check your Element,Button in this case..

A button can be disabled in many ways...so you will need to think about that but a simple solution would be the assertAttribute command, using the attribute disabled.

This will ensure the element has the disabled value set, which is a common way to disable elements, but not the only way.

In WebDriver. There is a method isEnabled which returns true if the element is enabled else it returns false.

driver.findElement(By.id("elementID")).isEnabled();