If your Internet Explorer browser has updated itself to version 11, this forces Exchange 2010 webmail to display in the 'light' version with less options and other websites to display strangely. This is a known issue.
A workaround is to add the webmail or website address into what is called the 'compatibility view' list, and it will then display as normal.
The easiest way to add it is to -
4. The box 'Add this website' should already have the webmail domain listed. If not, add the address (no http required) eg. exchange.yourdomain.com and click Add.
5. Click Close.
6. Close ALL browser windows and tabs and log onto webmail or browse to the website again, and it should display as normal.