If you play with list default pages like DispForm.aspx or EditForm.aspx or NewForm.aspx and after modification you find that anyone can’t see your modifications or if anyone trying to edit the page get this error
Unable to add selected web part(s). The file is currently checked out or locked for editing by another user.
You have to do the following , Simply check the file in , but the question is , from where can I check the file in ?
If you opened the file from SharePoint Designer under your list you will not find check-in option , you have to open it from “ All Files “ folder in SharePoint Designer , locate your file , check it in.