Site Titles and/or optional Taglines can be easily changed at any time here > Settings > General.
Not so when it comes to blog addresses ie. URLs. http://en.support.wordpress.com/changing-blog-address/
Note that if you do not purchase a site redirect upgrade then every links will be broken and all the page rank, authority and backlinks the original blog URLs has earned are gone forevermore.
If you do change your blog address, permalinks to your old address, including search engine results, will be broken unless you purchase a Site Redirect upgrade. http://en.support.wordpress.com/site-redirect/
7. The final option presented on this screen allows you to discard your current address. This option will permanently disable the address and you will not be able to reuse it. Only select this option if you are sure you will not use the address again. If you want to redirect traffic to the new blog, you can keep the address and purchase the Site Redirect upgrade.
It's too bad you ignored the 3 warnings and then clicked the verification link required to delete the blog. Deleted blog URLs are not recycled.
You can register another blog with a similar name. http://en.support.wordpress.com/register-a-blog/
Or you can register a domain via a domain mapping upgrade and it will not matter what the underlying .wordpress.com address is.