How to Solve GoogleBot Problem

Thankyou sir for reply me ,

now i  am get a message in webmaster tool :

www.govtjobsportal.com

	http://www.govtjobsportal.com/: Googlebot can't access your site - View details	Aug 21, 2013
	http://www.govtjobsportal.com/: Increase in not found errors - View details	Sep 6, 2013

(1)When Click >> www.govtjobsportal >>Crawl Error >>> It is sow three  type .1 DNS,  2. Server Conntectvity and 3 is Robots.txt Fetch .

When i am put the muse "DNS" Not Click only Mouse Put . It is Show "Couldn’t communicate with the DNS server" 

When i am put the muse "Server Conntectvity" Not Click only Mouse Put . It is Show "Request timed out or site is blocking Google"

When i am put the muse "Robots.txt Fetch" Not Click only Mouse Put . It is Show "Crawl postponed because robots.txt was inaccessible"

So please help me , How it Solve this problem and now my all keywords has not in your postion , this is not Top 400 Rank 

i will waiting your response .

Thnakyou