I can not clearly understand the verbs used with "de" and à

Question

I have 2 questions1-can I use indirect object or direct object  before the verb for "penser à" when I talk about people? and what is the rule for Je pense à Lui(tom) je lui pense or je le pense?? (does it work with any of them?)2-how can I inverted imperatif with penser à for peoplepense à moi  or pense moi (whicj one is true?)

Cécile Janty-Davies · Accepted Answer

Hi Hasan, 
With verbs like penser à, parler de and when talking about people, you will not use the direct or indirect pronouns but the stress ones. 
Je pense à elle=I am thinking of her 
Je pense à moi=I am thinking about me/myself
Je pense à eux= I am thinking about them 
Or
Je parle de lui= I am talking about him 
Je parle de moi = I am talking of me/myself 
It is the same for the imperative -
Pensez à moi!=Think of me! 
Parlez de lui=Talk about him 
The Kwiziq lesson on the stress pronouns ( they are the ones you use after chez) is below -
https://french.kwiziq.com/revision/grammar/common-uses-of-moi-toi-lui-elle-nous-vous-eux-elles-disjunctivestress-pronouns
There is quite a lot of grammar contained in your question and could go on but hope it helps!