Windows Vista How to Restore Windows Aero Transparency After Adjusting Graphics Settings

I bought my new laptop and I know it had the transparent windows and I could even change the colour to carbon and to red and change the transparency of the different colours but recently I wanted to get more out of my graphics so I turned everything to minumum including resolution and windows theme so I could play games more efficiently but now I can't find the transparent windows again and I can't see a windows aero setting and I know 100% that I could do it before I changed the settings.