Visible layers and stringing - bad quality


Hi everyone, let me explain you my problem.
I bought an Ender 3 for Christmas, and I started from January 3D printing. I have done lots of things and I was surprised about the quality of the results: in fact all the things I had printed were as they had to be. Then, after two months, suddenly things started to come in a orrible way: the main problem is that it seems like the printer uses too much filament, and all the layers are clearly visible, and while the printer is travelling from a point to another it doesn’t stop melting the filament (like it did in the past) but makes visible strings, like they were part of the layers.
I’ve tried lots of things and solutions that I found on the internet, but no one of them succeeded: so I wish someone here can help me, because the next step I will take as a solution is to take the printer and crush it with the car.
All of this problems with PLA.
Thank you everyone, I’m going to post a photo to make you see what the older prints looked like and what is happening now.

(P.S. I’ve tried in the midtime to print with ABS, but I’ve faced all these problems with some prints still in PLA before the ABS)