The LCD on our landline phones has become illegible. Is there a way to
restore the LCD, or do we just go get new phones?
Is it missing segments or faded out?
If there are segments missing, it's probably time to replace the phone.
There are some things you could try but they're iffy at best. For
instance, you can disassemble the glass from the PCB, clean the contact
areas, and reassemble. This only works if the display is built using a
silicone "zebra strip" connector between the glass and PCB, and even
then only works if dirty contacts are the actual problem. (They usually
aren't). If that's not it there's probably a dead driver and most
displays are chip-on-board and so not practically repairable.
If the display is losing contrast, there may be a battery someplace that
needs to be replaced. Our kitchen phone takes 4 AA's (!) but they last
over 5 years; when they start to go the display begins fading. We're on
our third set of batteries -- do the math -- so it may be time for us to
replace that phone anyway