Block on an accelerating wedge 
In the above figure, the wedge is been accelerated towards right as shown in figure. According to my teacher it is possible to keep the block at rest or even accelerate it in the upward direction along the the inclined plane of wedge. To explain he taught us about pseudo forces. Stating that in the Wedge frame we can assume a pseudo force in the right on the block as shown in figure.

He also said that we can also do the same from ground frame but when I am trying to do it I am not finding any force that resists the motion of of the wedge down the inclined plane.
 A: 
According to my teacher it is possible to keep the block at rest or even accelerate it in the upward direction along the the inclined plane of wedge.

I think  you are confusing the words of your teacher. What your teacher is actually trying to say is that it is possible to keep the block at rest or even accelerate it in the upward direction with respect to the wedge and what you perceived is that it is possible to keep the block at rest or accelerate it upwards with respect to ground which is absolutely incorrect.
Let's understand it through a thought experiment, consider the following  bullet train  with a block kept on it, suppose there is no friction. Now let us consider the motion of the block from different frames when the train is accelerating.

*

*Train frame
Suppose we are moving along the train with the same acceleration and speed. Then there are three possible motions of the block that we can see

*

*Block moving downwards with respect to the train when the trains acceleration is very low.

*Block at rest with respect to the train.

*Block moving upwards with respect to train along its inclined top. This is the extreme case where the train is accelerating quite fast.

All of this can be explained using pseudo force that you depicted in your diagram.



*Ground Frame
Now let us analyse the situation from the ground frame. What do we see if we see the above scenario while standing on the ground ?
Let us examine the extreme case of block moving upwards, when standing on the ground we will see that the block is climbing the incline top of the train as well as moving forward so the net movement of the block will be at some angle to the horizontal like this  in the above figure the net acceleration of the block is depicted with pink coloured vector along with its components, the horizontal component will be deducted when the observer is moving along the train so he sees the block to be moving upwards only.
The above motion can be explained by the following diagram 
The other sceneries can be explain in similar manner.

Note : A scenario in which the net motion of the block is along the incline top of the train is not possible as there is no force that supports this motion.
The net acceleration cannot be inclined to the left of horizontal as shown below. The reason why the above scenario is not possible it is because in order for it to be possible the force along the incline plane must be greater than the force along the horizontal which is not possible.
And you can cross check it from your own tron fbd as the force along the incline plane is $ma cos \theta $ which is always less than $ma$ itself.

Thus the net acceleration of the block from ground frame is always towards right of the vertical axis as shown below.
Hope it's clear to you now.
A: In the laboratory frame, The equation of motion given by

$$N\cos\theta-mg=0$$
$$N\sin\theta =ma$$
In Accelerating frame, The equation of motion given by

$$N\cos\theta-mg=0$$
$$N\sin\theta-ma=0$$
Both are equivalent.
