my website looses ranking what to do for SEO?

[LonestarG]

My stupid Boss is firing me because our website decreased. I changed the website since the first website was really bad and the first designer spammed all over and there were a lot of untitled webpages and there was not content management system our new website has a better look but somehow at first days when i submitted the site map it got higher ranking and then it began loosing it. I am not sure if my website is even getting indexed but with some keywords i can see it on the 4th or 5th page. I tried to add some back-links but my stupid boss is not giving money so i can submit the website to some high ranking directories.
No i get less calls but i see a good traffic to my website not like before. I pinged, and tried to renew articles and content also write blogs which apparently working other thing that i like to know is My designer created a file so google robots will not follow the old links is that a good idea or i should have created a 404 page? - or 303? How can i improve the site ranking in a week,!!! i have till 30th~