In cases when SharePoint cannot load the default page for a team site caused by adding a faulty web part, "Web Part Maintenance" page can help the site admin to remove the fault web part or reset the page to its default setting. While a link to this page is available on the "Edit Item" form for pages added to document library, adding "?contents=1" to the end of the URL for default page will cause a redirect to the "Web Part Maintenance" page for default.aspx.

More info can be found at : Customize Web Parts