My daughter's HP G70 laptop often will have striation lines on it, making it unusable. We've noticed that sometimes if you press down hard on the main unit, near the hinge where the screen is, that sometimes that clears up the striated lines and you can use it again, but this doesn't always fix it. What could be causing the striated lines and how might I fix it?
This is often caused by either broken parts or a loose connector.
Given that pressing down near the hinge (where a flat cable is usually connects the laptop's main board to the LCD) it is likely the latter.
HP's manual shows that part of your laptop as follows (see page 3-2).
This is usually easy to fix yourself (I have done it half a dozen times), but that will void your warranty. If it still under some warranty: Let the manufacturer fix it.
If you feel comfortable doing so yourself:
Test if possible; reassemble if it works.
If it does not work then you can either disassemble the screen and check that for faults, but that is usually a lot harder to do. If you go that way check the manual, page 3-9/