help on re-submitting and getting a new sitemap.xml

i had submitted my xml sitemap on google and bing webmaster tool...
but now for some reason it gives a general HTTP error: 404 not found
i had uploaded the sitemap.xml file through my ftp application on webserver..
but now its not there.. can anyone help me to get my sitemap.xml file a new one.. because the old file i dont know might have gotten deleted...
it seems i cant find it anywhere on webserver...
or is it there something i missed... what would be the standard procedure to upload the xml file on webserver...
i'm a newbee... so please dont mind... i'm confused..

There are free site map generator available use that to create one. Search "site map generator" in google.
It should be located exactly here domain.com/sitemap.xml if you placed it in different locations then you face these problem.

Downloaded the sitemap.xml file..
So now i'll just use a ftp application to upload it in webserver... and than resubmit the url in bing and google webmaster tools..

dude downloaded and added the file her domain.com/sitemap.xml
resubmitted the url, now it gives error
Missing XML tag This required tag is missing. Please add it and resubmit
what should i do..