Please use the Question Tag feature to add the name and full version number of the Story Format you are using, as answers can vary based on that information.
Based on the facts you mentioned "autosave" & "Load" and that SugarCube is the only story format that has both of these, I will assume you are using SugarCube 2.
background: Many HTML elements (like <button>) have a disabled attribute which can be used to disabled that element. SugarCube 2 is using this attribute to make the "Autosave "feature's "Load" unselectable.
There are a number of different ways you can use the disabled attribute with a button in SugarCube, one of them is using HTML Attributes combine with a HTML button element to create the button within your passage.
<button data-passage="Next" disabled>Go to the next passage</button>
... the above creates a disabled button that would transition the story to the "Next" passage if it could be selected.
To re-enabled that button you will need to give it a means to be identified and the simplest way to do that is to give the button element an unique ID like so.
<button id="next-button" data-passage="Next" disabled>Go to the next passage</button>
<<link "Enable the above Next button">>
To style your HTML button element so that it looks the same as those generated by the <<button>> macro you would assign your element the same CSS classes.
<button id="next-button" class="link-internal macro-button" data-passage="Next" disabled>Go to the next passage</button>
... these can be determined by using the Inspect feature of your web-browser's Web Development tools to inspect the CSS associated with the HTML output of a <<button>> macro.