non-selectable lines

[Mahsa Tsl]

Hello everyone, 
I am facing with a strange problem in my viewport, I see some small lines which I could not select them anywhere. I just see them when I go to the " Fit in window" view. they seem to be very far from my project they make my file really heavy. I also uploaded a photo, you can see these lines in the left upper part of the picture. 
would be happy if anyone can help me to solve it

[Barry Kelly]

It looks like you either have the main model itself very far from the project origin, or you have other elements that are very far from the model and hence very far from the project origin.

Always try to model close to the project origin.

In your plan view, select all (CTRL+A) while the arrow tool is active.

Then deselect the area around the model (I assume that is in the middle of your image).

Does that leave those bits off to the side selected?

If so delete them and see what happens - I assume being so far away they are not wanted?

Before you start deleting things, make sure you have a duplicate copy of you file.

Just in case you delete something you really need.

When you are happy, you can delete the duplicate file.

Barry.