How do I rectify a problem when I open up my messenger box with a particular friend and it is in precious mome

My messenger box opens in precious moments imvironment and the bottom goes behind the task bar. I cant drag it up and the send portion is hidden therefore I cant send messages to my frien d or even send offline messages . this imvironmennt seems to have expanded recently . I can drag the top bit up but it only stretches the whole box. I cant reply to my friend now unless I ask her to come in on no imvironment. I cant change my box to no imvioronment and I am stuck. I have a small screen monitor but there was not a problem before There iis no problen in no imvironment Help please