Question: I know this is not a technical related question.But i do not have any idea.I am going to develop a project which should be supported in both phone and tablet.Is it possible having one project working for both tablet and phone ?

Answer: 
MySql can handle very large projects, it's stable, updated and free, so I think you shouldn't think to go on with Access.  

Connecting to MySql will be quite easy: include MySql.Data.dll and change db connection string, it's easy and you'll find a lot of examples on internet.  

If your app should only talk with db in intranet, simply install MySql on a server and connect your app using server ip and port.
I have seen Access database have real poor security and which is terribly slow. If at all you intend to open your access database after a few days of running in production, you will see the how slow it can be. 

Though it looks like you are new to MySQL, you will not need much of a learning curve to work with it. MySQL have lot of users that you will get a good support for you MySQL related questions also. And the best of all you will be able to learn MySQL, which i am sure you will use later for other applications you create.