Pulling Previous Data Value Using an API

[John1]

Hello! I have some leads that were updated accidentally and I would like to revert those values to a previous one. I know that it's not something you can do since there isn't an undo function in Marketo but I know that it's possible to pull that information using an API. Does anyone have any resources on how to do it? I am new to using APIs and any help will be useful. A majority of the leads were fixed but there are still some that needs to be updated again. 

Is this something that I should do, definitely don't want to break anything, just want to pull information. I have some coding experience but nothing too crazy

[SanfordWhiteman]

You want the Get Lead Changes endpoint: https://developer.adobe.com/marketo-apis/api/mapi/#operation/getLeadChangesUsingGET

First, get a paging token (https://developer.adobe.com/marketo-apis/api/mapi/#operation/getActivitiesPagingTokenUsingGET) for the time you know the mistakes started and move forward from there.