It may happen that a post you wrote in WordPress is modified by error!
It happened to me: this morning when I went to see a two years old post of mine, I did not find anymore an information I was sure I wrote. May be it happened to you too, but don’t worry! You can recover any previous version of a post you saved, even after years and the procedure is very easy 😉

First check that, in Screen settings, it is checked the Revision checkbox:

Screen settings button

Revision checkbox

Then you can notice that there is a Revision item on the Publish right section, with the number of revisions that post has and a Scroll link that allows you to see all of them:

Revisions item with the Scroll link

You can move left the time arrow to get previous versions that post had during the time:

Move left the time arrow to get previous versions

When you reach the version of the post you want to restore, you have to click on the Recover this version button:

Click on the Recover this version button to get back the old selected version

You can find the list of all revisions also at the botton of the edit page, in the Revision section where you can select one of them too:

List of all revisions at the botton of the edit page