On this morning, i am still using this database,
but now my database seem like crashed, and display this error to me.
how can i solve this problem other than recreate the database?

Do you have access to the DB itself? Access to this server?

what you means that?
i just normal refresh the database like everytime you reopen your VB, the connection of database sure lost so i did click the refresh button to make the sure connection is okay.

Now my database is work fine with my desktop, this problem is come out from my laptop, what the problem? i am afraid when i present my project will occur this problem again because of using laptop to present.

Ok so you have this instance running on your network and you get this error from your laptop.

A network related problem would result in this type of error.

If you are on a laptop connected wifi make sure the network is up and running.

Since you are trying to connect from a different computer, you have to make sure that your desktop that is hosting the DB allows remote connections, your firewall allows it, etc...

Where you able to connect from the laptop before?

i able to connect from some cafe that are wifi available. Once i go to my friend house (wifi available also) i connected to the wifi because before i go to show my project to my friends, i go listen some music from youtube. :x

So if you are able to connect most of the time, that indicates that your configuration is correct.

However, you have to keep in mind that wifi connectivity depends on more than traditional wired access. This issue you are having is not SQL, but a network problem. When you get this error, troubleshoot it as a network related problem.