In my house there is 2 wires the black one and the red one, what could happen y for example I touch both wires with my hand. we have 120 V, Pd. somehow we tried to install a lamp there but didn´t work. I have googled it and it says that if i have sweety hands i will get only 12 mA that will hurt me but it won´t be fatal so what could happen?
In the US or Canada, you will probably find 240 volts between the red and black wires, but 120 volts from either one to the white (neutral) wire.
DO NOT TOUCH AC POWER WIRES WITH YOUR HANDS!!
A 120 Volt or 240 Volt shock can cause serious injury!
what could happen if for example I touch both wires with my hand?
Death is a certain possibility.
If you do not know how to check for "liveness" then you also risk creating a fire - or just killing yourself or someone else.
Best is to use a test meter - an AC voltmeter suited to 120 VAC operation.
You COULD use a mains rated lamp with two test probes (wire ends) with 2 INSULATED LEADS - and be aware that you could kill yourself.
If you touch the two test leads on a power source elsewhere and the bulb lights and it does not happen on your target wires they MAY not be live.
One could be live and the other not - this may not light the bulb BUT MAY still KILL YOU.
A theme is developing here :-( :-(.
If the wires were live at one time there may be a blown fuse or a removed fuse or a circuit breaker that is turned off. If so, restoring power to the circuit, may restore power as desired, or just may set the building on fire. And along the way it just may kill you.
Having an electrician or knowledgeable friend have a look for you is a very very good idea.
As stated do not touch AC POWER WIRES WITH YOUR HANDS or any sort of wires if you have to ask. If your lamp doesn't work, measuring the voltage with your body is one of the worst ways to figure out if the voltage is on. A local hardware store can probably instruct you in the equipment you need to detect if they outlet is working or not.
A dramatization of the effects of touching wires can be seen in the video below with some description of how environmental (like shoes) effects can play a role: https://www.youtube.com/watch?v=TwIvUbOhcKE