Désassortir is a french second group verb. So it follow the regular conjugation pattern of the second group like: 
finir. Follow this link to see all the endings of the conjugation of the second group verbs : 
conjugation rules and endings for the second group verbs.
																												
																												Désassortir is conjugated the same way that verbs that end in : 
-ir.
																												The prototypical verb for the second conjugation is 
finir. The conjugation is, marked by the vowel 
i and the infix 
-iss- in the indicative present and imperfect.																												
																																																																																																		
Désassortir is conjugated in interro-negative form. The interro-negative form being obtained by inversion of the subject, the placement of the negative adverb follow the same rules as in negative form, giving the following rules:
									
 - in interro-negative form, the adverb 
« ne » is always placed first if the subject is a pronoun.
									
 - in simple tenses, the adverbs (
« ne ...pas », 
« ne...plus », 
« ne...jamais », etc...) surround the verb 
désassortir and the inverted subject pronoun.
									
 - in compound tenses or in passive voice, the negative adverbs surround the auxiliary and the inverted subject pronoun.
																		
																			
For sound reasons, like in interrogative form, an euphonious 
« t » is added to the pronoun of the third person: 
« il », 
« elle », 
« on », 
« ils », 
« elles » except when the verb ends with 
« t » or 
« d »: 
« ne désassortira-t-elle pas ? », 
« n'a-t-elle pas désassorti ? », 
« n'aura-t-elle pas désassorti ? ».
																											
Finally, the interrogative form does not exist in subjunctive and imperative.