Problems configuring OSPF in Packet tracer

[ayalafreire7]

I have been trying to configure OSPF in a topology with 5 routers, but routers 2 and 4 cannot get any neighbors with OSPF. I can't do any ping between the PCs either. The network was configured using VLSM.

The topology file in the packet tracer is attached

[Martin L]

Be careful assigning IPs to interfaces.  It often happens in VLSM; Your IPs do not match interfaces; wrong IP on interface link  to R1 and to R5, aka  R4-R1 serial interfaces are mixed up R4-R5 .

Similarly there must be same mistake on left side; I think R1 has mixed up IP to interface. Also check your passive interface status

Regards, ML
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[NetworkDave]

@ayalafreire7,

In addition to what @Martin L advised:

The IP addresses on the serial interfaces for Routers R2 and R4 are incorrect; The host addresses configured do not belong to the assigned network.

R2 S2/0 (83.253.137.9/30) change to R2 S2/0 (83.253.137.2/30)
CIDR & Subnet Mask: /30 & 255.255.255.252
Network Address: 83.253.137.0
Usable Host IP Range: 83.253.137.1 - 83.253.137.2

R2 S3/0 (83.253.137.2/30) change to R2 S2/0 (83.253.137.9/30)
CIDR & Subnet Mask: /30 & 255.255.255.252
Network Address: 83.253.137.8
Usable Host IP Range: 83.253.137.9 - 83.253.137.10

Router R1 is not configured to establish a neighbor adjacency with R2.
On Router R1, remove "passive-interface Serial2/0" parameter.

After changes are made and OSPF verified, check connectivity.

HTH
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[LisaNichols]

Due to the changed IP address that's why you are facing the issue, for better understanding, you can consider the above 2 replies. 

[LisaNichols]

Here are some steps to help diagnose and resolve the OSPF configuration problems in Packet Tracer:
Verify that OSPF is enabled on all routers:
Router#show running-config | include router ospf
Verify that the OSPF process is started on all routers:
Router#show ip ospf
Verify the OSPF router ID on all routers:
Router#show ip ospf | include Router ID
Verify that the OSPF network type is correctly configured on all routers:
Router#show ip ospf interface <interface_name>
Verify that the OSPF hello and dead intervals are set to the same values on all routers:
Router#show ip ospf interface <interface_name>
Verify that the OSPF area ID is correctly configured on all routers:
Router#show ip ospf interface <interface_name>
Verify that the OSPF network mask is correctly configured on all routers:
Router#show ip ospf interface <interface_name>
Verify that the OSPF neighbors are up on all routers:
Router#show ip ospf neighbor
Verify that the OSPF routes are correctly learned on all routers:
Router#show ip route ospf
Check the PC configurations and ensure that they have the correct IP addresses, subnet masks, and default gateways.

Verify that there are no ACLs blocking OSPF messages or network traffic between the PCs.

By following these steps, you should be able to diagnose and resolve the OSPF configuration problems in Packet Tracer.