- How many day should I wait for an E-Mail before assuming they are not interested in me?
Zero. In fact, zero minutes. Immediately after you have applied, forget it, and move on to apply to next company. By "forget it" I mean that you previous applications should not stop you in any way proceeding with other applications. Your success depends very much on volume, the more companies you apply to, the better changes you have to find one that is interested in you.
Also, "forget it" in a sense, that you don't dwell on it, especially with cases where you don't get any response or get a rejection.
However, "forget it" does not mean, that you should not make follow up:
- If I don't got any reply even after considerable time, should I E-Mail them again asking for a reply?
Yes. Call or email, but do understand that companies do get a lot of internship applications and might not be very responsive no matter what.