True ricotta is a whey cheese. It is relatively easy to make provided you have access to a decent volume of whey and the ability to heat and strain it. I'd say you'd probably want around 10L of whey to make the effort worth your while.
Because of the low yield associated with traditional ricotta recipes, some home cheese-makers choose to augment the recipe by cutting the whey with a quantity of milk. This will dramatically increase the yield, but may affect the flavour and texture of the cheese.
As others have suggested, if cottage cheese is available where you are it may provide a suitable substitute. Especially if you blend it a little first to make it smoother. Paneer is very easy to make at home, but has a much firmer texture than ricotta. I have never experimented with tofu as a ricotta substitute myself, but it seems that a soft tofu might be suitable.
It is also very easy to make a simple soft fresh cheese by culturing a few L of milk with a tablespoon or so of buttermilk.
Heat 10L of whey (from a rennet cheese NOT direct acidified) to 60C in a covered pot.
Add 30mL of vinegar (and 60mL of salt if desired).
Slowly increase heat to 80-90C, checking periodically for the formation of curds. (I find it usually takes about 40-50 minutes.)
Ideally three "eyes" should form on the surface of the curds, although this does not always happen.
The curds should look somewhat dry on the surface when they are done.
Strain through cheesecloth and allow whey to completely drain from curds.
In my experience, this recipe makes about 100g of ricotta per L of whey used. However, I use sheep milk and whey. I would expect the yield to be roughly halved when using cow's milk/whey.
Warm 2L of cream (10-20% butterfat content; preferably pasteurized at low temperatures, UHT milk will NOT work) to 32C.
Add 15mL buttermilk.
Leave to culture for at least four hours. The cream should thicken (into sour cream). You may also see a small amount of whey separating out from the cream.
Strain through butter muslin or a double layer or cheesecloth.
This should produce a fresh, light, slightly tangy spreadable cheese. The flavour and texture are different than that of ricotta, but you may find it a palatable substitute nonetheless. And it may be easier for you to make than true ricotta.