I assume you mean a browser hijack virus. It is worth checking the settings menu for your browser - I use google chrome, so for me it would be settings /on startup / open a specific page or set of pages. Click the link next to it and it shows the address to which the browser is set to open to. In other browsers, this might be listed as the homepage.
Make sure it is set for the homepage you particularly want - www.google.co.uk got example, and delete any other choices.
In more general terms you may wish to use a couple of free malware and spyware scanners/removers. Google "Hijack This" and "Malwarebytes" and run those now, and then every so often going forward.
Hopefully that is pretty clear :)
If you need help though, you may want to be a little more precise in the details of your problem. Type of browser you use, homepage, etcetc....