You do not say what operating system you are using.
But you can download drivers for that model laptop from the Lenovo website.
The website link is:http://support.lenovo.com/en_US/default.page
There are a few options to find the correct model so you can download the correct driver.
For example, if you choose Browse Products under the support website, you will see a dropdown list of menu options.
On the first menu, choose
Laptops & netbooks
3000 Y series laptops
At this next page is where you will want to choose the model. The model number is to the right of the number 7757 so it will be 7757-xxx where xxx=the model number
then choose your operating system
Once you see your laptop listed at the top, choose the menu option on the left called
Download Drivers & Software
As an alternative to the above which is somewhat difficult, you can just download the Lenovo system updater program which you can run to make sure you download the correct drivers: