Some configurations of adobe reader has change.I can't get them back.Can you help me.I encircled the functions with red color in the pic
Does your problem affect all files or just one? If the latter, have you checked the document's security settings to see whether commenting is disabled?
The latest versions of Adobe Reader have a stupid GUI (IMO) where buttons on the toolbar just get deleted if Adobe thinks there is no room to display them.
Right-click anywhere on the toolbar, and you get a set of menus with all the available functions. If you select something, the corresponding icon will probably appear on the toolbar but something else will disappear to make room for it.