Search has stopped working suddenly

Question

I am getting following error when I search for anything:

We did not find any results for KEYWORD. Suggestions:

Ensure words are spelled correctly.
Try using synonyms or related searches.
Try broadening your search by searching from a different site.
Try removing search refinements or using more general keywords.

Additional resources:

Get additional search tips by visiting Search Help
If you cannot find a page that you know exists, contact your administrator.

I think crawler has stopped working and hence there is no indexing for search.

Additional info provided by @shobs :

Hello I am the administrator for this site Saumilm is referring to.

The crawl was working fine all along and when the mysite was added to the content source the crawl stopped working and it started crawling ohter test application in the farm.

Here is the error message:

The start address 'http://xxx.xxx.org' cannot be crawled.

Context: Application 'SharePoint_Server_Search', Catalog 'Portal_Content'

Details:

Item not crawled due to one of the following reasons: Preventive crawl rule; 
Specified content source hops/depth exceeded; URL has query string parameter; 
Required protocol handler not found; Preventive robots directive. (0x80040d07)

Answer 1

Unless you have removed your index it should still be there, check your Search Service Administration page and see if you have any crawl history. If there are errors you can check them through the crawl log and that should tell you what is going on.

Answer 2

You should also verify that the password has not expired on the Search and Crawl service accounts.

Answer 3

check whether search service is running.