I'm also having this exact same problem. I was able to change my homepage back to its default, but have no clue as to how to change by default search back to Google.

Try to reset some preferences to the default with the SearchReset extension:

• https://addons.mozilla.org/firefox/addon/searchreset/

Note that the SearchReset extension only runs once and then uninstalls automatically, so it won't show on the "Firefox > Add-ons" page (about:addons).

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance).

• Do not click the Reset button on the Safe mode start window or otherwise make changes.

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

If you do not keep changes after a restart then see:

• http://kb.mozillazine.org/Preferences_not_saved

EcoStartpage.com is a malicious browser hijacker. This redirection and automatic homepage settings are done by a malware application. anyhow, you have to scan your system with an anti-malware tool to detect and remove this infection, or you may delete it manually by eliminating this virus` components How to remove EcoStartpage browser hijack virus