Is increased here used as an adjective like "window is broken"?
a) My salary is not increased.
b) Prices are increased.
c) Profit for this month is increased.
I am aware that increased is Transitive Verb but still without doer we can understand the meaning that rise in the level of salary, Price and profit.
We can Interpret above sentences as Passive voice without doer.
a) Salary Increased by Organisation.
b) Prices Increased by Seller.
c) Profit Increase by a Company.
Ignoring some other grammatical problems in the OP (see the answer by Steve Kass), the answer to the question is:
Yes. 'Increased' is an adjective in those situations (your first three example sentences). The type of adjective is called a "predicate adjective".
Note that both the past and present participles of verbs, i.e. the -ed and -ing forms if the verb is regular, are routinely used as adjectives.
"Predicate adjectives" are defined in CMoS 5.81 as follows:
A predicate adjective is an adjective that follows a linking verb (see 5.99) but modifies the subject. [Examples are the child is afraid; the night became colder; and I feel bad.]
CMoS 5.99 defines "linking verbs" as follows:
A linking verb is one that links the subject to an equivalent word in the sentence--a predicate pronoun, predicate noun, or predicate adjective. The linking verb itself does not take an object. There are two kinds of linking verbs: be-verbs and intransitive verbs that are used in a weakened sense, such as seem, smell, appear, feel, and look.
I think most English speakers would say
To emphasize an unnamed doer, you could say
Profit is not generally increased by a doer, so I left that one out.
The comparison with “window is broken” doesn’t work well. “Broken” is an inherent state; you can look at a window and tell if it is broken. You can’t look at a salary and tell if it “is increased.” Something is increased if it is changed from a previous value. Also, because something is “increased” only if a change has taken place before now, the past tense is used (“has increased” or “was increased”).
[Added: To answer the OP’s specific question, I don’t think “increased” is as “adjective-y” in these examples as “broken.” You could replace “My window is broken.” with “My window is a broken window,” if slightly awkwardly, but it would be more awkward to say “My salary is an increased salary.” However, increased can be an adjective: “Increased prices caused a drop in sales.” “The increased speed limit may be the cause of the recent spate of accidents.”]
