I had the same problem with my fish eating all my cory eggs all the time everytime they layed them and i found this was the best technique for making them survive;
a. Get a spoon or somthing that is flat but doesn't have a sharp edge and carefully prize the corys eggs off the tank glass/plants- they break very easily so you must be very careful, they are very sticky so just try to get them to stick to the spoon.
b. Get a long clean glass at hand and adjust it to the tank temperature for 30mins- you can speed this process up by running it under warm water- you basically don't want the tank glass to be too hot or too cold but the same temp as the tank.
c. Fill the glass up with tank water halfway so it floats in the tank and carefully drop the cory eggs in the glass making sure they do not get exposed to the air.
d. Once you have done this cover the top of the glass with some netting and tie the netting to the glass and either
ii. tilt the glass so it doesn't sink somhow but gets some VERY gentle water flow from the filter or,
iii. just tip half of the water out fill it up with new tank water 3times a day or more(i found chose this technique at the time and it worked the best for me).
e. If the fry in the eggs are growing or are at least still alive the eggs will darken in color or remain the same color but if they go white this means the fry in them have died and the dead eggs should be removed to avoid them getting fungus and it spreading to the rest of the live eggs and killing them- incidentally, remove any eggs that get fungus ASAP as this will only proceed to kill the whole batch; fungus is your main fear here and is very common in fish eggs.
Making sure the eggs get fresh tank water everyday will help prevent fungus from getting in and also keeping water stats top notch as posible.
f. Now just sit back and wait for the eggs to hatch- word of advice: albino cory fry are virtually invisable, they are see through and with a touch of white outlining in their body and so keep an eye out for when they hatch as it is very easy to miss them.
As soon as they start hatching, start feeding them very small amounts of liquifry no.1 for egglayers and move them to a cycled fry tank after a couple of days- its best to use a see-through glass for all this as it makes it much easier to spot the fry
.
I tried putting the eggs in a breeding trap or net in the past before i figured out this method but mortallity rates were high in fry and thats if the eggs ever hatched, which they usually didn't in a net.