Webpart To view all documents of a user in MySite

Thank you for the clarification. I'm a massive fan of search, especially for these types of requirements. You just need to remember that you'll need to wait for search to crawl the content before it appears.

On your page, you can add (assuming you've got SP2013 Enterprise) a Content Search web part (This can be found in your web part toolbox, under the Content Rollup category), or a Search Results web part (found under the Search Category once you have activated the Search Server Web Parts Site Collection Feature).

Edit your chosen web part and select "Change Query".

As you want to display content from anywhere within SharePoint, you can remove the path query, unless you're indexing data sources from outside of SharePoint as well. 

Change you query to look like this:

(IsDocument:"True") EditorOWSUSER:{User.Name}

IsDocument:"True" will remove list items from your results and only show documents (this includes aspx pages)

EditorOWSUSER:{User.Name} will match the modified by field to the user who runs the query (the logged in user)

If you want to filter your query down even more you could add the following to specify file types:

(FileExtension:doc OR FileExtension:docx OR FileExtension:xls OR FileExtension:xlsx OR FileExtension:ppt OR FileExtension:pptx OR FileExtension:pdf)

As long as the user has permissions to the content source, they will see their documents in the results.