Dvd drive cant read dvds but can read vcds - LG (GCC-H23NB) CD-RW/DVD-ROM Combo Drive

First of all, are you trying to read Blu-Ray DVDs? Unless your drive is made for them, it won't be able to. The same may be true if you're trying to read a dual-layer DVD. Not all DVD drives can handle them.

CDs and DVDs need different kinds of laser light to be read, and a combo drive like yours is essentially two drives in one. Sometimes a problem develops in the pickup and it can read one kind of disc and not the other. My experience is that it's usually the DVD function that fails more often. The data on a DVD is much more densely packed and harder to read.

Try making sure the discs you're trying to read are clean. If the problem is affecting all the DVDs you try, replace the drive. New drives for a desktop computer only cost around $20 to $30 and they are easy to change. In a laptop, the drive will be more expensive and maybe hard to find; in that case you may want to consider a USB external burner as a replacement. This is also an option for desktops as well.