What are some good homemade foods that are the easiest to prepare? I live in a country where street-food is hazardous, 99% restaurants are unhygienic and the rest of 1% restaurants are either extremely expensive(as compared to my level of income) for everyday-meal or unavailable in the neighborhood, and, packed foods(like cereal, cornflakes, etc.) are also unavailable. I am also not a food-enthusiast and very lazy to cook.

I have gas stove. I don't have oven.

Readily eatable vegetables are not available. For example, tomatoes, lettuces, broccoli and cucumbers are not available. Fruits are totally imported and consequently very expensive. Even if they were available, raw vegetables or fruits do not stay in the stomach for long and eating only raw fruits gives acidity.

Cheap available foods are rice,  broiler-meat, lentils, wheat-flour. Mutton and beef are expensive. Liquid milk is unavailable. Powdered milk is expensive. Fish is very messy to buy and cook. Eggs are not healthy to eat thrice a day. All types of spices are available but packed spices are little expensive. Vegetables are available but takes time to sanitize, but, I fear peeling.

Can anyone please tell me what kind of foods can I adapt for my everyday life that are cheap, need least effort to prepare, healthy, keep me working for a long time and do not need freezing to preserve?

Please suggest me some single-pot meals that are easy to cook. Unattended cooking must be the priority.
Usually cheap and fast don't go together. For example the cheapest cuts of meat can be the most delicious if cooked slowly for a long time. Root vegetables (potatoes, carrots, parsnips, turnips) are delicious roasted, especially in olive oil (frankly everything is, even large summer squash that is almost tasteless transforms in the oven) but they need about an hour. If you have an oven and a microwave, I suggest cooking in the evening (perhaps after eating) and then reheating that the next day for you your lunch and dinner. 

The other direction would be pasta (bought or made; it takes time to make it but you can make it one evening and cook it the next) or rice with a sauce made from canned (or cooked by you the previous day) ingredients. The sauce should either have a little meat, or have something to complement the grain protein: that will be either legumes (beans, lentils etc) or dairy (cheese, yogurt etc). 

I think your best bet will be to do something each night after dinner that works towards your next night's meal. That will give you quick meals when you're hungry, but with the yumminess that time-of-cooking can provide.