My media queries wont work please help me

I think you have an extra bracket at the bottom of the page, but you definitely have working media queries, There are a few issues I see:

1. You should indent and space your CSS consistently across the entire page. This:

.class{color:red padding:1px;
margin: 3px:}

Is much harder to read than:

.class{
    color: red 
    padding: 1px;
    margin: 3px:
}

It's also much easier to see the missing semi-colon in the second one.

1. Your media queries are repetitive, any screen that is greater than 1051px is also greater than 750px, so the 750px rules still apply. There's no need to apply 90% width to .wrapper at the 1051px query if you've already applied that rule to the 750px query, in fact the only rule that does anything in your 1051px query is the max-width rule.

I hope that is at least a little helpful, I'm not positive what you want each query to do, so I can't help you unless I knw what you want to do. Remove the bracket, change to px, and add a background-color to banner to confirm the query is working even if it's not acting as you want it to. I suspect you may have an extra character in a rule that I missed in due to the formatting. Good luck!