om swastik belpatra

How can I learn tantrik vidyas? Can you guide me and teach me?

Tantrik Vidya and other tantra related stuff should be learnt from a well practicing Guru. Yes you can start your path in the field by having initiation in Tantra.

Can any body take Guru diksha from two different Guru?

Yes, he can. A person should stick to His first Guru until and unless He found someone more fulfilling. If a person feels the first Guru is not responding the way He should than he can think of moving to another.

Generally not recommended until and unless you feel a non-dominating desire to choose another Guru.

Having two Guru may cause dichotomy. So its better to have the first one or the second one.

But, for example, one find that the guru or the path chosen by him is not according to his personality or attitude He can search for a new Guru. Actually the his true Guru will find him if he have a will.

What is the power of guru mantra? Simply chanting guru mantra can be fulfill anything or not?

Everything said in the sacred texts can be attained by reciting Guru mantra only. Simply chanting guru mantra can fulfill everything. All your queries are related to this question. for the power to chant guru mantra, you will need to Put aside your desires. Than the stage will come when everything you wish is fulfilled. But this need a few basic things to follow which a Guru will direct you.

Is there any means of achieving goal or fulfill a desire?

Guru Diksha and Seva is one of the ways. A guru mantra leads you to your final aim and goal. The mantras gave
enough vision to  fulfill desires. The process may be slow sometimes.

Guru is always there to guide you when you find you are in dark.