Ajit, you did not say what your foundation was made of but I will assume that it is cast concrete. You will need a hammer and chisel to clean out the crack. One straight solid steel chisel and about a 2 pound hand sledge will probably be about right. Buy fairly good quality as they will take a beating and there is nothing worse than worrying about the head flying off the sledge while you are trying to work. Go along the crack with the chisel from about 1" on both sides of the crack chipping back the concrete square or undercut to the wall for a depth of 3/4".
Then buy hydraulic cement and a small trowel. Thoro Waterplug is one brand of cement but I'm sure that there are others available at different home centers. Mix the cement per the label directions and apply it with the trowel until it is flush to slightly raised over the old concrete wall and let it set up. Thoro says that a 2-1/2 pound container will fill a space 3/4" wide by 3/4" deep by 75" long.
While you might try to keep the cement off your hands, chances are that you will get some on them. You can try to work in gloves but this has always proven to be difficult for me. The lime in the cement will cause your hands to dry out and hurt. To prevent this, the best thing that I have found is called Bag Balm, available at mass marketers in this area. Apply this to your hands after you have washed the cement off your hands and dried them. You may be able to find other hand creams, but this really works.