diagnostics found no reason for lines. Now i have vertical and horizontal

If you are experiencing vertical and horizontal lines on your MacBook Air's display and the diagnostic tests have not detected any issues, there are a few troubleshooting steps you can try:

1. Reset the NVRAM/PRAM.

2. Reset the SMC.

3. Check display settings.

4. Boot your MacBook Air in Safe mode.

5. External display.

If none of these steps resolve the issue, it may be necessary to contact Apple Support or visit an authorized service provider for further assistance. They will be able to diagnose and repair any underlying hardware problems that might be causing the lines on your MacBook Air's display.

The screen is bad and needs to be replaced.

At this point you need to schedule a service appointment at your local Apple Store or AASP and get an estimate.

Mac Repair & Service - Apple Support

I will second den.thed's response, that based on what you have provided, your Mac's screen appears to be faulty.

Otherwise, you really haven't provided us with many details. For example, did this laptop experience a liquid spill, or was it dropped? ... or you used a screen protector with it?

Fortunately, or unfortunately the Apple Diagnostics cannot catch everything ... so, using it alone, will not rule out potential hardware issues.

Without knowing much on what you are experiencing or what you have tried to resolve it, all we can offer is that you contact Apple Support directly for assistance with this issue. To do so, simply select the "Support" link on the lower left-hand side of this forum's web page.

Sorry, I wasn't trying to sound accusatory, just that we have little information that led up to this issue. If, as you say, the screen was working fine, but then developed these lines, something happened.

Again, there is nothing any of us can do to "fix" this for you. As a number of us have already implied, it's time to have Apple Support assist you with a resolution. Good luck!