Screen resolution problem in Lubuntu

Hello, people,

I'd like to talk about a difficult that I've been facing last days.

I'm not a pro user of Lubuntu, so that brings me packages of ignorance in solving the problems.

My notebook is a Dell Inspiron N4030 and I have got a screen resolution problem since I installed Lubuntu 17.04 in my PC days ago: the only resolution "option" that I have (in xrandr apt) is 1024x768 , in spite of my notebook having the maximum capacity of 1366x768 (AMD ATI Mobility Radeon HD 5430). So the screen is kind of 'horizontally stretched' and a little bit smaller that I'd like to have. I tried some methods, like these:

https://ubuntuforums.org/showthread.php?t=2269341

https://help.ubuntu.com/community/Lu...tor_or_Screens

https://askubuntu.com/questions/8675...ion-in-lubuntu

but none worked for me.

Can somebody help me? I've been feeling kind of frustrated for that :\\

Thanks, anyway. Hugs!